Question

If sinx=2/3 then find cos2x

Answer 1

Answer:

Step-by-step explanation:

sin x = 2/3

also sin x = p/h

or p = 2

and h= 3

As per Pythagoras theorem ,

$h^2 = p^2 + b^2$

or $b^2$ = $h^2 - p^2$

or $b^2$ = 9 - 4

or b = $\sqrt{5}$

so cosx = b/h = $\sqrt{5}$/3

sin2x = 2sinxcosx

or sin2x = 2 × 2/3 × $\sqrt{5}$ /3 = 4$\sqrt{5}$/9