trigo identities. proving!! help me with this.. please

Question

trigo identities.  proving!! help me with this.. please

anonymous · Answer

wait..

anonymous · Answer

:)

anonymous · Answer

rsin theta = r^3cos^3 theta/ 2a - r costheta

anonymous · Answer

i need to get the real answer which is 2a sin theta tan theta..

ranga · Answer

The left side may have to be r^2sin^2(theta)  if this is derived from your previous problem.

anonymous · Answer

yes yes

anonymous · Answer

now im lost..

anonymous · Answer

so what are the correct terms? the ones above are wrong?

anonymous · Answer

r^2sin^2 theta = r^3cos^3 theta/ 2a - r costheta

ranga · Answer

Multiply throughout by (2a/r).  
You will have a quadratic equation.  Solve for r.

anonymous · Answer

the a and r are throwing me, we never played with that in these equations.
cos^3 = 1-sin^2(theta)cos(theta)

anonymous · Answer

actually this is a cartesian to polar conversion..

anonymous · Answer

im backing out lol

ranga · Answer

Why don't you give the original problem here too.

anonymous · Answer

what level of math do we see this in?

anonymous · Answer

analytic geometry

anonymous · Answer

y^2 = x^3 / 2a - x

anonymous · Answer

I didnt see it in trig, ahh I haven't taken that.

anonymous · Answer

and i need to derive r= 2a sin theta tan theta