Activity 4: Intercepts of a Circle given the Graph
The intercepts are the points where the graph touches the x- and y-axis. The point that passes through the
x-axis is called x-intercept, and the point that passes through the y-axis is called y-intercept.
In the graph of the circle, 𝑥 2 + 𝑦 2 = 16, the following are the intercepts.
x-intercepts:
(-4, 0) and (4, 0)
y-intercepts:
(0, 4) and (0, -4)
Using the above example, find the radius of the circle by graphing each equation in Desmos.
1. 𝑥 2 + 𝑦 2 = 4
x-intercepts: ____________________
y-intercepts:_______________________
2. 𝑥 2 + 𝑦 2 = 25
x-intercepts: ____________________
y-intercepts:_______________________
3. 𝑥 2 + 𝑦 2 = 9
x-intercepts: ____________________
y-intercepts:_______________________
4. 𝑥 2 + 𝑦 2 = 1
x-intercepts: ____________________
y-intercepts:_______________________
5. 𝑥 2 + 𝑦 2 = 64
x-intercepts: ____________________
y-intercepts:_______________________
6. 𝑥 2 + 𝑦 2 = 100
x-intercepts: ____________________
y-intercepts:_______________________
7. 𝑥 2 + 𝑦 2 = 81
x-intercepts: ____________________
y-intercepts:_______________________
8. 𝑥 2 + 𝑦 2 = 144
x-intercepts: ____________________
y-intercepts:_______________________
9. 𝑥 2 + 𝑦 2 = 49
x-intercepts: ____________________
y-intercepts:_______________________
10. 𝑥 2 + 𝑦 2 = 225
x-intercepts: ____________________
y-intercepts:_______________________