Hi CFem

Question 1

let :

Find x

Question 2

let :

Now can you draw a right angle triangle and set the value of adjacent side and hypotenuse, then find y ?

Question 3

let : arc tan (x) = p , so cos(2 [arc tan x] ) = cos (2p)

arc tan (x) = p

tan (p) = x

Now draw a right angle triangle then set the value of opposite and adjacent side, then use double angle formula to simplify cos(2p)