Question

If tan2A = cot(A-${18}^{\circ }$), then value of A (in degrees) is:

• A. 36

Answer 1

The correct option is A 36

Given, tan 2A = cot (A - ${18}^{\circ }$)

$\Rightarrow$ tan 2A = tan (90 - (A - ${18}^{\circ }$)

$\Rightarrow$ tan 2A = tan (${108}^{\circ }$ - A)

$\Rightarrow$ 2A = ${108}^{\circ }$ - A

$\Rightarrow$ 3A = ${108}^{\circ }$

$\Rightarrow$ A = ${36}^{\circ }$