Answer:
2.5π
Step-by-step explanation:
First, let's find the circumference of the circle. The circumference is equal to dπ, or the diameter times π.
Knowing the diameter is 10, we can easily find that the circumference is 10π.
10π is the entire circumference, but we only need 90° of the circle. If the whole circle is 360°, then that means the portion we need is 90°/360°, which is 1/4.
1/4 times 10π is equal to 2.5π.
2.5π is the arc length.
