91Ó°ÊÓ

In Exercises 21-40, find the quotient \(\frac{z_{1}}{z_{2}}\) and express it in rectangular form. $$ z_{1}=25\left[\cos \left(\frac{13 \pi}{9}\right)+i \sin \left(\frac{13 \pi}{9}\right)\right] \text { and } z_{2}=5\left[\cos \left(\frac{7 \pi}{9}\right)+i \sin \left(\frac{7 \pi}{9}\right)\right] $$

In Exercises 29-44, use a calculator to express each complex number in polar form. Express Exercises 29-36 in degrees and Exercises 37-44 in radians. $$ 8-6 i $$

In Exercises 13-40, perform the indicated operation, simplify, and express in standard form. $$ (12-18 i)(-2+i) $$

In Exercises 21-40, convert each point given in polar coordinates to exact rectangular coordinates. $$ \left(\frac{5}{2}, 330^{\circ}\right) $$

In Exercises 21-36, each set of parametric equations defines a plane curve. Find an equation in rectangular form that also corresponds to the plane curve. $$ x=\sin t, y=\sin t $$

In Exercises 29-44, use a calculator to express each complex number in polar form. Express Exercises 29-36 in degrees and Exercises 37-44 in radians. $$ -3+4 i $$

In Exercises 21-40, find the quotient \(\frac{z_{1}}{z_{2}}\) and express it in rectangular form. $$ z_{1}=30\left[\cos \left(\frac{3 \pi}{2}\right)+i \sin \left(\frac{3 \pi}{2}\right)\right] \text { and } z_{2}=15\left[\cos \left(\frac{\pi}{6}\right)+i \sin \left(\frac{\pi}{6}\right)\right] $$

In Exercises 21-40, convert each point given in polar coordinates to exact rectangular coordinates. $$ \left(\frac{3}{4}, 225^{\circ}\right) $$

In Exercises 13-40, perform the indicated operation, simplify, and express in standard form. $$ (-4+3 i)(-4-3 i) $$

In Exercises 21-36, each set of parametric equations defines a plane curve. Find an equation in rectangular form that also corresponds to the plane curve. $$ x=\cos t, y=-\cos ^{2} t $$