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Law of Sines: Solving for an AngleLaw of Sines: Solving for an Angle
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Question 1 of 5
1. Question
Find θRound your answer to the nearest minute- θ= (67)° (32)′
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Sine Law
asinA=bsinB=csinCwhere:
a is the side opposite angle A
b is the side opposite angle B
c is the side opposite angle CWhen to use the Sine Law (for non-right angled triangles)
a) Given 2 sides and 1 angle to find the other angleorb) Given 2 angles 1 side to find the other sideCalculator Buttons to Use
sin = Sine functioncos = Cosine functiontan = Tangent functionDMS or ° ‘ ‘‘ = Degree/Minute/SecondShift or 2nd F or INV = Inverse function= = Equal functionDegree-to-Minute Conversion
1 degree =60 minutesMinute-to-Second Conversion
1 minute =60 secondsRounding Off to the Nearest Minute
If the seconds is greater than or equal to 30”, round the minute up.
If the seconds is less than 30”, round the minute down.First, label the triangle according to the Sine Law.Substitute the three known values to the Sine Law to find the fourth missing value.From labelling the triangle, we know that the known values are those with labels b,B,c and C.b=29 cmB=θc=18 cmC=35°bsinB = csinC 29sinθ = 18sin35° Substitute the values 18×sinθ = 29×sin35° Cross multiply 18×sinθ÷18 = 29×sin35°÷18 Divide both sides by 18 sinθ = 29×sin35°18 sinθ = 16.63271718 Use the calculator to simplify sinθ = 0.9240954 θ = sin-10.9240954 sin inverse Simplify this further by evaluating sin-10.9240954 using the calculator:1. Press Shift or 2nd F (depending on your calculator)2. Press sin3. Press 0.92409544. Press =The result will be: 67.5323°Round off the answer to the nearest minute.θ = 67.5323° = 67°31’56” Press DMS on your calculator = 67°32’ Round up since the seconds is greater than 30” 67°32’ -
Question 2 of 5
2. Question
Find θRound your answer to the nearest degree- θ= (62)°
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Chapters- Chapters
Sine Law
asinA=bsinB=csinCwhere:
a is the side opposite angle A
b is the side opposite angle B
c is the side opposite angle CWhen to use the Sine Law (for non-right angled triangles)
a) Given 2 sides and 1 angle to find the other angleorb) Given 2 angles 1 side to find the other sideCalculator Buttons to Use
sin = Sine functioncos = Cosine functiontan = Tangent functionDMS or ° ‘ ‘‘ = Degree/Minute/SecondShift or 2nd F or INV = Inverse function= = Equal functionDegree-to-Minute Conversion
1 degree =60 minutesMinute-to-Second Conversion
1 minute =60 secondsRounding Off to the Nearest Minute
If the seconds is greater than or equal to 30”, round the minute up.
If the seconds is less than 30”, round the minute down.First, label the triangle according to the Sine Law.Substitute the three known values to the Sine Law to find the fourth missing value.From labelling the triangle, we know that the known values are those with labels p,P,r and R.p=92 mP=24°r=200 mR=θpsinP = rsinR 92sin24° = 200sinθ Substitute the values 92×sinθ = 200×sin24° Cross multiply 92×sinθ÷92 = 200×sin24°÷92 Divide both sides by 92 sinθ = 200×sin24°92 sinθ = 81.3473392 Use the calculator to simplify sinθ = 0.88421 θ = sin-10.88421 sin inverse Simplify this further by evaluating sin-10.88421 using the calculator:1. Press Shift or 2nd F (depending on your calculator)2. Press sin3. Press 0.884214. Press =The result will be: 62.15447°Round off the answer to the nearest degree.θ = 62.15447° = 62°9’16” Press DMS on your calculator = 62° Round down since the minutes is less than 30’ 62° -
Question 3 of 5
3. Question
Find θRound your answer to the nearest degree- θ= (74)°
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Chapters- Chapters
Sine Law
asinA=bsinB=csinCwhere:
a is the side opposite angle A
b is the side opposite angle B
c is the side opposite angle CWhen to use the Sine Law (for non-right angled triangles)
a) Given 2 sides and 1 angle to find the other angleorb) Given 2 angles 1 side to find the other sideCalculator Buttons to Use
sin = Sine functioncos = Cosine functiontan = Tangent functionDMS or ° ‘ ‘‘ = Degree/Minute/SecondShift or 2nd F or INV = Inverse function= = Equal functionDegree-to-Minute Conversion
1 degree =60 minutesMinute-to-Second Conversion
1 minute =60 secondsRounding Off to the Nearest Minute
If the seconds is greater than or equal to 30”, round the minute up.
If the seconds is less than 30”, round the minute down.Since the values given are opposite each other, we can directly substitute them to the Sine Law.a=51.4 mA=θb=52.9 mB=82°asinA = bsinB 51.4sinθ = 52.9sin82° Substitute the values 52.9×sinθ = 51.4×sin82° Cross multiply 52.9×sinθ÷52.9 = 51.4×sin82°÷52.9 Divide both sides by 52.9 sinθ = 51.4×sin82°52.9 sinθ = 51.4×0.99026852.9 Use the calculator to simplify sinθ = 50.899778752.9 sinθ = 0.9621886 θ = sin-10.9621886 sin inverse Simplify this further by evaluating sin-10.9621886 using the calculator:1. Press Shift or 2nd F (depending on your calculator)2. Press sin3. Press 0.96218864. Press =The result will be: 74.1938°Round off the answer to the nearest degree.θ = 74.1938° = 74°11’ Press DMS on your calculator = 74° Round down since the minutes is less than 30’ 74° -
Question 4 of 5
4. Question
Find the obtuse angle αRound your answer to the nearest degree- α= (131)°
Hint
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Chapters- Chapters
Sine Law
asinA=bsinB=csinCwhere:
a is the side opposite angle A
b is the side opposite angle B
c is the side opposite angle CWhen to use the Sine Law (for non-right angled triangles)
a) Given 2 sides and 1 angle to find the other angleorb) Given 2 angles 1 side to find the other sideCalculator Buttons to Use
sin = Sine functioncos = Cosine functiontan = Tangent functionDMS or ° ‘ ‘‘ = Degree/Minute/SecondShift or 2nd F or INV = Inverse function= = Equal functionDegree-to-Minute Conversion
1 degree =60 minutesMinute-to-Second Conversion
1 minute =60 secondsRounding Off to the Nearest Minute
If the seconds is greater than or equal to 30”, round the minute up.
If the seconds is less than 30”, round the minute down.Substitute the three known values to the Sine Law to find the fourth missing value.a=37mA=αb=16mB=19°asinA = bsinB 37sinα = 16sin19 Substitute the values 16×sinα = 37×sin19° Cross multiply 16×sinα÷16 = 37×sin19°÷16 Divide both sides by 16 sinα = 37×sin19°16 sinα = 12.046021716 Use the calculator to simplify sinα = 0.75287636 α = sin-10.75287636 sin inverse Simplify this further by evaluating sin-10.75287636 using the calculator:1. Press Shift or 2nd F (depending on your calculator)2. Press sin3. Press 0.752876364. Press =The result will be: 48.8401549°Round off the answer to the nearest degree.α = 48.8401549° = 48°50’ Press DMS on your calculator = 49° Round up since the minutes is greater than 30’ Notice that the result is an acute angle even though the actual angle is supposedly obtuse. This is because we used the Sine Law.To get the obtuse angle, simply subtract the angle from 180°.α = 180-49 α = 131° 131° -
Question 5 of 5
5. Question
Find the obtuse angle αRound your answer to the nearest degree- α= (150)°
Hint
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Incorrect
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Subtitles- subtitles off
Captions- captions off
- English
Chapters- Chapters
Sine Law
asinA=bsinB=csinCwhere:
a is the side opposite angle A
b is the side opposite angle B
c is the side opposite angle CWhen to use the Sine Law (for non-right angled triangles)
a) Given 2 sides and 1 angle to find the other angleorb) Given 2 angles 1 side to find the other sideCalculator Buttons to Use
sin = Sine functioncos = Cosine functiontan = Tangent functionDMS or ° ‘ ‘‘ = Degree/Minute/SecondShift or 2nd F or INV = Inverse function= = Equal functionDegree-to-Minute Conversion
1 degree =60 minutesMinute-to-Second Conversion
1 minute =60 secondsRounding Off to the Nearest Minute
If the seconds is greater than or equal to 30”, round the minute up.
If the seconds is less than 30”, round the minute down.Substitute the three known values to the Sine Law to find the fourth missing value.a=128mA=αb=99mB=23°asinA = bsinB 128sinα = 99sin23 Substitute the values 99×sinα = 128×sin23° Cross multiply 99×sinα÷99 = 128×sin23°÷99 Divide both sides by 99 sinα = 128×sin23°99 sinα = 50.01358499 Use the calculator to simplify sinα = 0.5051877 α = sin-10.5051877 sin inverse Simplify this further by evaluating sin-10.5051877 using the calculator:1. Press Shift or 2nd F (depending on your calculator)2. Press sin3. Press 0.50518774. Press =The result will be: 30.343815°Round off the answer to the nearest degree.α = 30.343815° = 30°20’ Press DMS on your calculator = 30° Round down since the minutes is less than 30’ Notice that the result is an acute angle even though the actual angle is supposedly obtuse. This is because we used the Sine Law.To get the obtuse angle, simply subtract the angle from 180°.α = 180-30 α = 150° 150°
Quizzes
- Intro to Trigonometric Ratios (SOH CAH TOA) 1
- Intro to Trigonometric Ratios (SOH CAH TOA) 2
- Round Angles (Degrees, Minutes, Seconds)
- Evaluate Trig Expressions using a Calculator 1
- Evaluate Trig Expressions using a Calculator 2
- Trig Ratios: Solving for a Side 1
- Trig Ratios: Solving for a Side 2
- Trig Ratios: Solving for an Angle
- Angles of Elevation and Depression
- Trig Ratios Word Problems: Solving for a Side
- Trig Ratios Word Problems: Solving for an Angle
- Area of Non-Right Angled Triangles 1
- Area of Non-Right Angled Triangles 2
- Law of Sines: Solving for a Side
- Law of Sines: Solving for an Angle
- Law of Cosines: Solving for a Side
- Law of Cosines: Solving for an Angle
- Trigonometry Word Problems 1
- Trigonometry Word Problems 2
- Trigonometry Mixed Review: Part 1 (1)
- Trigonometry Mixed Review: Part 1 (2)
- Trigonometry Mixed Review: Part 1 (3)
- Trigonometry Mixed Review: Part 1 (4)
- Trigonometry Mixed Review: Part 2 (1)
- Trigonometry Mixed Review: Part 2 (2)
- Trigonometry Mixed Review: Part 2 (3)