Question

(0,7): Use the equation r^2=x^2+y^2 to find the radius of this point.

Answer 1

Answer:  $(7,\frac{\pi}{2})$

Step-by-step explanation:

Given

The equation of the circle is $x^2+y^2=r^2$

Point $(0,7)$ lies on the circle

Put the value

$\Rightarrow 0^2+7^2=r^2\\\Rightarrow r=7\ \text{units}$

for this point, the angle is given by

$\Rightarrow \tan \theta=\dfrac{y}{x}\\\\\Rightarrow \tan \theta=\dfrac{7}{0}\rightarrow \infty$

That is $\theta \rightarrow 90^{\circ}$

The polar coordinate is given by $(r,\theta)$

$\therefore\ (7,90^{\circ})\ \text{or}\ (7,\frac{\pi}{2})$