Trigonometry

What is cos(A+B)cos(A-B)?

If cos A = 4/5, find tan(A/2).

Simplify: sin(A+B)sin(A-B).

Value of tan 75 + cot 75 is:

The expression 4 cos^3 A - 3 cos A equals:

Simplify cos(60+A) + cos(60-A).

If tan A = x, then sin 2A is:

If A + B + C = 180, then tan A + tan B + tan C is equal to:

Solve: sin 10 sin 30 sin 50 sin 70

If A+B+C = 180, then cos 2A + cos 2B + cos 2C = ?

Find the value of tan 6 tan 42 tan 66 tan 78.

In a triangle ABC, sin 2A + sin 2B + sin 2C equals:

If tan(A/2) = t, then cos A = ?

What is the value of cot 15 + cot 75?

In triangle ABC, cos^2 A + cos^2 B + cos^2 C = ?

Simplify: cos x / (1 - sin x)

Value of sin^2 10 + sin^2 20 + ... + sin^2 90 is:

If cos A + cos B = 0 and sin A + sin B = 0, then cos(A-B) is:

The value of tan 20 + tan 40 + sqrt(3) tan 20 tan 40 is:

If sin A + sin B + sin C = 4 cos(A/2) cos(B/2) cos(C/2), then A+B+C is: