Question

let cosx- 1/sqrt10 with x in Q4 and find cot 2x

Answer 1

write cot(2x) in terms of cos(x) and sin(x).
find sin(x) using cos(x)=1/sqrt(10) (you can do this by drawing a right triangle in quadrant 4)

Answer 2

if you have questions please let me know

Answer 3

ok but what about the double angle formulas for tangent?

Answer 4

cot(2x)=cos(2x)/sin(2x)
use cos(2x)=cos^2(x)-sin^2(x)
and sin(2x)=2sin(x)cos(x)