Test 4 Section 4 Number 24

Because the question tells you that segment *AB* is a diameter, you know that arc *ADB *is exactly half the circumference of the circle. If the length of the arc is 8*π*, therefore, the full circumference of the circle must be 16*π*.

How do we solve for the radius if we know the circumference? We use the formula for circumference (provided at the beginning of the section if you don’t have it memorized).