1.Two circles are concentric, and have radii of 15 and 25 respectively. If two arcs are formed by the same central angle, which of the following are possible arc lengths? Select the two correct answers.

Question

-30 and 40
-3 and 5
-60 and 90
-45 and 75
-50 and 80

2.Two circles are concentric. Two arcs are formed by the same central angle, with arc lengths of 54 and 81 respectively. Which of the following are possible radii for the circles? Select the two correct answers.
-12 and 18
-23 and 32
-32 and 64
-40 and 60
-14 and 41

Answer 1

#1. the ratio is 15:25 = 3:5
#2. The ratio is 54:81 = 6:9