**Problem : **
Solve the following equation:
*cos*(*x*) - tan^{2}(*x*) = 1
.

**Problem : **
Solve the following equation:
2 sec(*x*)sin^{3}(*x*) = cos(*x*)tan^{2}(*x*)
.

**Problem : **
Calculate
cos(15)
using the fact that
cos(30) =
.

**Problem : **
*θ*
is in the first quadrant, and
tan(*θ*) =
. Find
the sine, cosine, and tangent of
2*θ*
.

**Problem : **
Express the following as a function of a single angle:
.

**Problem : **
Express the following as a sum or difference:
cos(100)cos(50)
.

**Problem : **
Simplify:
sin^{2}(*x*) + cos^{2}(*x*) - sec^{2}(*x*) + tan^{2}(*x*)
.

**Problem : **
Solve:
cos(*x*)tan(*x*) = csc^{2}(*x*) - cot^{2}(*x*) - 1
.