How do you convert x^2 + 5xy + y^2 = 7x2+5xy+y2=7 to polar form?

1 Answer
May 1, 2016

r^2=7/(1+5/2sin2theta)r2=71+52sin2θ

Explanation:

To convert from Cartesian to Polar coordinates use the following formulae which link them.

• x=rcostheta , y=rsintheta x=rcosθ,y=rsinθ

rArr r^2cos^2theta+5r^2costhetasintheta+r^2sin^2theta=7r2cos2θ+5r2cosθsinθ+r2sin2θ=7

remove the common factor of r^2r2

rArrr^2(cos^2theta+5costhetasintheta+sin^2theta)=7r2(cos2θ+5cosθsinθ+sin2θ)=7

Simplify using trig. identities

• sin^2theta+cos^2theta=1" and "sin2θ+cos2θ=1 and

• sin2theta=2sinthetacosthetasin2θ=2sinθcosθ

rArrr^2(1+5/2sin2theta)=7r2(1+52sin2θ)=7

rArrr^2=7/(1+5/2sin2theta)r2=71+52sin2θ