Answer:
a) cosθ = [tex]\frac{-2\sqrt{85} }{85}[/tex]
Step-by-step explanation:
Step(i):-
Given point ( x , y ) = ( - 2 , 3 )
We know that the polar co-ordinates
x = r cos θ and y = r sinθ
where [tex]r = \sqrt{x^{2} +y^{2} }[/tex]
[tex]r = \sqrt{(-2)^{2} +(9)^{2} } = \sqrt{4+81} = \sqrt{85}[/tex]
Step(ii):-
x = r cos θ
cosθ [tex]= \frac{x}{r}[/tex]
cosθ = [tex]\frac{-2}{\sqrt{85} } = \frac{-2}{\sqrt{85} } X \frac{\sqrt{85} }{\sqrt{85} }[/tex]
cosθ = [tex]\frac{-2\sqrt{85} }{85}[/tex]
