If cos 2x 79 find tan x for pi SolutionSolution Given Cos2x

Solution

Solution:

Given: Cos2x = 7/9

By formulla

Cos2x = (1 - tan^2 x) / (1 + tan^2 x)

7/9 = (1 - tan^2 x) / (1 + tan^2 x)

7(1 + tan^2 x) = 9(1 - tan^2 x)

7 + 7 tan^2 x = 9 - 9 tan^2 x

16 tan^2 x = 2

tan^2 x = 1/8

tan x = 1/8 = 1/(22)   for pi < x < 3pi/2

or

.tan x = 1/(22) = (2)/4