Show that the equation 3sinxtanx = 8 can be written as 3cox^2x + 8cosx - 3

Question

asked Mar 25, 2019 15.3k views

1 Answer

Vanson Samuel · Answer 1 · 2019-03-31T07:41:03+0000

using the trigonometric identities

tanx =
(sinx)/(cosx) and sin²x = 1 - cos²x

3sinxtanx = 8

( 3sin²x)/ cosx = 8 ( multiply both sides by cosx )

3( 1 - cos²x ) = 8cosx

3 - 3cos² = 8cosx ( subtract 3 - 3cos²x from both sides )

0 = 3cos²x + 8cosx - 3