Trig Identities

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

Value of cos(pi/7) cos(2pi/7) cos(4pi/7) is:

In ABC, cot A/2 + cot B/2 + cot C/2 = ?

Simplify (1 + sin 2A + cos 2A) / (1 + sin 2A - cos 2A).

If x = r cos T sin P, y = r cos T cos P, z = r sin T, then x^2 + y^2 + z^2 = ?

The maximum value of 3 sin x + 4 cos x is:

Simplify sin^6 A + cos^6 A + 3 sin^2 A cos^2 A.

If cos A / a = cos B / b, then the triangle is:

Value of tan 20 tan 40 tan 80 is:

Simplify: cos^2 A + cos^2(A+120) + cos^2(A-120).

If A+B+C = 180, then sin^2 A + sin^2 B - sin^2 C = ?

The expression (cos 11 + sin 11) / (cos 11 - sin 11) is:

Find the value of sqrt(2 + sqrt(2 + 2 cos 4A)).

In triangle ABC, tan A/2 tan B/2 + tan B/2 tan C/2 + tan C/2 tan A/2 = ?

If cos A + cos^2 A = 1, then sin^2 A + sin^4 A = ?

What is the value of sin 18?

Simplify (sin 5A - sin 3A) / (cos 5A + cos 3A).

The value of cos 1 cos 2 cos 3 ... cos 179 is:

If sin x + cosec x = 2, then sin^2 x + cosec^2 x = ?

In a triangle, if sin^2 A + sin^2 B + sin^2 C = 2, the triangle is: