Trigonometric Functions & Identities

put cos²x=1-sin²x in second equation

we will get sin²x (1+sin²x)

now put cos2x = 1 - 2 sin²x in equation one we will get sin²x =cosx

so we have to find the value of cosx*(1+cosx)

now put cos2x =  2 cos²x -1

u will get cosx*(1+cosx) = 1