Question

Cosx=4/5 what is sin2x cos2x and tan2x

Answer 1

Answer:

-24/5

Step-by-step explanation:

The solution to the problem is as follows:

cscx < 0 means 1/sinx < 0, or sinx < 0.  

sinx = -3/5 because you're dealing with a 3-4-5 triangle, and we established

sinx is negative.  

sin2x = 2sinxcosx = 2*-3/5*4/5 = -24/25  

cos(2x) = cos^2(x) - sin^2(x) = 16/25 - 9/25 = 5/25 = 1/5  

tan2x = sin2x / cos2x = -24/5