Question

Show that the point is on the unit circle.

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

Short answer

The point$\left(\frac{3}{5},-\frac{4}{5}\right)$ is on the unit circle.

Step-by-step solution

Step 1. State the definition of the unit circle.

The unit circle is the circle of radius $1$ centered at the origin in the $xy$- plane. It is given by the equation $x^2+y^2=1$.

Step 2. Substitute the points.

In order to show that the point satisfies the equation of the unit circle, substitute$\frac{3}{5}$ for role="math" localid="1648203502717" $x$ and$-\frac{4}{5}$ for $y$ into the equation$x^2+y^2=1$.

$\begin{array}{r}{x}^2+y^2\stackrel{?}{=}1\\ {\left(\frac{3}{5}\right)}^2+{\left(-\frac{4}{5}\right)}^2\stackrel{?}{=}1\end{array}$

Step 3. Simplify and state the conclusion.

Simplify the expression.

$$\begin{gathered} {\left(\frac{3}{5}\right)}^2+{\left(-\frac{4}{5}\right)}^2\stackrel{?}{=}1 \\ \frac{9}{25}+\frac{16}{25}\stackrel{?}{=}1 \\ \frac{25}{25}\stackrel{?}{=}1 \\ 1=1\text{True} \end{gathered}$$

Therefore, the point is on the unit circle.