Question

If tan A – tan B = x and cot B – cot A = y, then the value of cot (A – B) is

Answer 1

Answer:

Let A = 18°

Therefore, 5A = 90°

⇒ 2A + 3A = 90˚

⇒ 2A= 90˚ - 3A

Taking sine on both sides, we get

sin 2A = sin (90˚ - 3A) = cos 3A we know , sin(90 - A) = cos A

⇒ 2 sin A cos A = 4cos^3 A - 3 cos A using formulas for sin 2A and cos 3A

Answer 2

Let A = 18°

Therefore, 5A = 90° =

- 2A + 3A = 90°

→ 2A= 90° - 3A

Taking sine on both sides, we get

sin 2A = sin (90° - 3A) = cos 3A we know, sin(90 - A) = cos A

→ 2 sin A cos A = 4cos^3 A - 3 cos A using formulas for sin 2A and cos 3A....

Hope it's helpful for you.....