Answer to Question #165350 in Trigonometry for Arianne Orfila

Question

y= -3 cos 2 (x+π/5)

Answer 1

Given equation is -

$y=-3cos2(x+\dfrac{\pi}{5})$

Putting y=0 in the above equation we get,

$\Rightarrow 0=-3cos(2x+\dfrac{2\pi}{5})$

$\Rightarrow 2x+\dfrac{2\pi}{5}=cos^{-1}0$

$\Rightarrow 2x=1-\dfrac{2\pi}{5}$

$\Rightarrow x=\dfrac{5-5\pi}{10}$

Also putting x=0 in eqs.(1) we get-

$y=-3cos\dfrac{2\pi}{5}$

$=-3(0.3090)=-0.92$

The Graph of the given equation is-