EXAMPLE 2
Solve
a trigonometric equation
Solve the equation sin θ
= –
where
180° < θ < 270°.
5
8
SOLUTION
STEP 1
sine is –
is sin–1 – 38.7°. This
5
8
5
8
–
Use a
calculator to determine that in the
interval –90° θ 90°, the angle whose
≤
≤
angle is in
Quadrant IV, as shown.