parametric equations :(

[Mel Mitch]

I don't understand the trigs....please guide me

Problem

Find the cartesians equation for the following parametric form

x=2 sin A, y=cos A

 

[Mel Mitch]

hi again...in the problem above they also said to remember sin^2 A + cos^2 A= 1

sorry about that......thanks in advance..

Mel Mitch

 

[BigGlenntheHeavy]

\(\displaystyle x \ = \ 2sin(A) \ and \ y \ = \ cos(A)\)

\(\displaystyle x^{2} \ = \ 4sin^{2}(A), \ sin^{2}(A) \ = \ \frac{x^{2}}{4} \ and \ y^{2} \ = \ cos^{2}(A).\)

\(\displaystyle Ergo, \ \frac{x^{2}}{4}+y^{2} \ = \ sin^{2}(A)+cos^{2}(A) \ = \ 1, \ an \ ellipse.\)

 

[Mel Mitch]

thanks again.....i was wondering how to get it into that form.....now i could use that to arrive at
x^2 + 4y^2 = 4 as the answer