Thread: Trigonometric functions question!

Hey, the question is:

Show that the equation tan x = 4cos x may be written as

4sin^2x + sin x -4= o

Anyone know how to do this? Thanks!

Hello, LoveDeathCab!

Show that the equation: .tan x .= .4·cos x

may be written as: .4·sin²x + sin x - 4 .= .0

. . . . - . . .sin x
We have: .------ .= .4·cos x
. . . . - . . .cos x

Multiply by cos x: .sin x .= .4·cos²x


Then we have: .sin x .= .4(1 - sin²x) . → . sin x .= .4 - 4·sin²x


Therefore: . 4·sin²x + sin x - 4 .= .0