In: Advanced Math
1. Find a Cartesian equation for the curve.
r cos(θ) = 2
Identify the curve.
2. Find a Cartesian equation for the curve.
r = 4 sin(θ)
Identify the curve.
The above diagram shows the polar as well as Cartesian coordinates of a point P. The rectangle OAPB shows that AP=OB=y, OA=BP=x, OP=r. Then, by trigonometry on triangle OAP,
,.
1)
Now, the equation given is , and we know . So, the Cartesian equation is x=2, which is the straight line passing through (2,0) and parallel to the y axis.
2)
Now, the equation given is . Now, ...(A)
Now,
Then, from (A):
,
So, the Cartesian equation of the given polar equation is , which is the circle of radius 2, centred at (0,2).