**Trig Functions of Angles**

**Sol 1** The reference angle for is
.
Since the sine is positive in Quadrant II,
.

**Sol 2** The reference angle for is
.
Since the cosine is negative in Quadrant III,
.

**Sol 3** The reference angle for is
.
Since the tangent is negative in Quadrant II,
.

**Sol 4** The reference angle for is
.
Since the cosine is positive in Quadrant IV,
.

**Sol 5** The reference angle for is
.
Since
and the cosine is negative in Quadrant III,
and
.

**Sol 6** The reference angle for is
.
Since
and the tangent is negative in Quadrant II,
and
.

**Sol 7** The reference angle for is
.
Since the tangent is positive in Quadrant III,
.

**Sol 8** The reference angle for is
.
Since
and the sine is negative in Quadrant IV,
and
.

**Sol 9** Since
,

and .

**Sol 10** Since , subtracting off a multiple of gives
; so
.
Since the reference angle for is
, and
since the sine is positive in Quadrant II,
.

**Sol 11** Since , subtracting off a multiple of gives
; so
.
Since the reference angle for is
, and since the
cosine is positive in Quadrant IV,
.

Return to the Problems for this
Topic.

Return to Precalculus Home Page.