Unit A: Geometry

Chapter 3: Trigonometry


Practice


Instructions: Click the Download File button to download a printable PDF of the questions. Answer each of the following practice questions on a separate piece of paper. Step by step solutions are provided under the Solutions tab. You will learn the material more thoroughly if you complete the questions before checking the answers.

1.
Use the sine law to find ∠ H .






2.
Use the sine law to find ∠ P .




1.
Use the sine law to find ∠ H .


 


Label  ΔABC.





The given information in ΔABC is

∠ C = 112 ° a = 5 . 6   cm c = 8 . 2   cm

∠ A ∠ H is across from side a = 5.6 cm ( ∠ A and side a are a matching pair.)
∠ C = 112 ° and is across from side c = 8.2 cm ( ∠ C and side c are a matching pair.)

sin Aa=sin Ccsin A5.6=sin 112°8.2sin A5.6×5.6=sin 112°8.2×5.6sin A=sin 112°8.2×5.6=0.6332∠A=sin-10.6332=39°
Check: Do you know 3 of the 4 parts of the formula?


Since ∠ A = ∠ H ,   ∠ H is equal to 39°.
Use the sine law to find ∠ P .





Label ΔABC.





The given information in Î”ABC is

∠C=71°b=2.8 mc=6.5 m

∠B is across from side b = 2.8 m. (∠B and side b are a matching pair.)
∠C=71° is across from side c = 6.5 m. (∠C and side c are a matching pair.)
∠A, or ∠P, is across from side a.

Since side a is not given, ∠A (or ∠P) cannot be yet be calculated. However, the sine law can be used to calculate ∠B.

sin Bb=sin Ccsin B2.8=sin 71°6.5sin B2.8×2.8=sin 71°6.5×2.8sin B=sin 71°6.5×2.8=0.4073∠B=sin-10.473=24°

Recall that the sum of the angles in a triangle is 180°. Use ∠A+∠B+∠C=180° to find ∠A.

∠A+∠B+∠C=180°∠A+24°+71°=180°∠A+95°=180°∠A=180°-95°=85°

Since ∠A=∠P, âˆ P is equal to 85°.