Precalculus Examples

$(\frac{- 5}{2}, \frac{π}{6})$

Step 1

Use the conversion formulas to convert from polar coordinates to rectangular coordinates.

$x = r c o s θ$

$y = r s i n θ$

Step 2

Substitute in the known values of $r = \frac{- 5}{2}$ and $θ = \frac{π}{6}$ into the formulas.

$x = (\frac{- 5}{2}) \cos (\frac{π}{6})$

$y = (\frac{- 5}{2}) \sin (\frac{π}{6})$

Step 3

Move the negative in front of the fraction.

$x = - \frac{5}{2} \cdot \cos (\frac{π}{6})$

$y = (\frac{- 5}{2}) \sin (\frac{π}{6})$

Step 4

The exact value of $\cos (\frac{π}{6})$ is $\frac{\sqrt{3}}{2}$ .

$x = - \frac{5}{2} \cdot \frac{\sqrt{3}}{2}$

$y = (\frac{- 5}{2}) \sin (\frac{π}{6})$

Step 5

Multiply $- \frac{5}{2} \cdot \frac{\sqrt{3}}{2}$ .

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Step 5.1

Multiply $\frac{\sqrt{3}}{2}$ by $\frac{5}{2}$ .

$x = - \frac{\sqrt{3} \cdot 5}{2 \cdot 2}$

$y = (\frac{- 5}{2}) \sin (\frac{π}{6})$

Step 5.2

Multiply $2$ by $2$ .

$x = - \frac{\sqrt{3} \cdot 5}{4}$

$y = (\frac{- 5}{2}) \sin (\frac{π}{6})$

$x = - \frac{\sqrt{3} \cdot 5}{4}$

$y = (\frac{- 5}{2}) \sin (\frac{π}{6})$

Step 6

Move $5$ to the left of $\sqrt{3}$ .

$x = - \frac{5 \sqrt{3}}{4}$

$y = (\frac{- 5}{2}) \sin (\frac{π}{6})$

Step 7

Move the negative in front of the fraction.

$x = - \frac{5 \sqrt{3}}{4}$

$y = - \frac{5}{2} \cdot \sin (\frac{π}{6})$

Step 8

The exact value of $\sin (\frac{π}{6})$ is $\frac{1}{2}$ .

$x = - \frac{5 \sqrt{3}}{4}$

$y = - \frac{5}{2} \cdot \frac{1}{2}$

Step 9

Multiply $- \frac{5}{2} \cdot \frac{1}{2}$ .

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Step 9.1

Multiply $\frac{1}{2}$ by $\frac{5}{2}$ .

$x = - \frac{5 \sqrt{3}}{4}$

$y = - \frac{5}{2 \cdot 2}$

Step 9.2

Multiply $2$ by $2$ .

$x = - \frac{5 \sqrt{3}}{4}$

$y = - \frac{5}{4}$

$x = - \frac{5 \sqrt{3}}{4}$

$y = - \frac{5}{4}$

Step 10

The rectangular representation of the polar point $(\frac{- 5}{2}, \frac{π}{6})$ is $(- \frac{5 \sqrt{3}}{4}, - \frac{5}{4})$ .

$(- \frac{5 \sqrt{3}}{4}, - \frac{5}{4})$