Question

How do you find the exact values of sin 2u, cos 2u, and tan 2u using the double-angle formulas given `tan u = 3/4`, `0 < u < pi/2`?

Answer 1

Call tan x = t = 3/4. Use trig identities in terms of `tan (a/2)`

`sin 2x = (2.t)/(1 + t^2) = (3/2)/(25/16) = 48/50`

`cos 2x = (1 - t^2)/(1 + t^2)` =