Simplify the expression by using a double-angle formula or a half-angle formula.

a. ((2 tan (5degres))/(1-tan^2(5degres)))

b. ((2 tan (5x))/(1-tan^2(5x)))

Do remember the formula:
tan(2y) = 2tan(y) / (1 - tan^2 (y))

a)

In this case, tan(y) = tan(5)

(2 tan(5)) / (1 - tan^2 (5))
= tan((2)(5))
= tan(10)

b)

In this case, tan(y) = tan(5x)

(2tan(5x)) / (1 - tan^2 (5x))
= tan((2)(5x))
= tan(10x)