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.