If sinx = cotx, then value of (cos^2(x)+2cos^3(x)+cos^4(x)-3)

Question

A) 0 B) -1 C) -2 D)-3

Answer 1

sinx = cotx
sinx = cosx/sinx
sin^2x = cosx
1-cos^2x = cosx
cos^2x + cosx - 1 = 0
cosx = (-1±√5)/2

I get -2
Now you can evaluate the expressions