The sum of radius of the two circles is 91 cm and the difference between their areas is 2002 cm2. What is the radius (in cm) of the larger circle?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 49 cm.
r1 + r2 = 91 .....(1)
πr12 - πr22 = 2002
⇒ r12 - r22 = 2002 × 7/22 = 637
⇒ (r1 - r2)(r1 + r2) = 637
⇒ r1 - r2 = 637/91 = 7 .....(2)
From (1) and (2):
r1 = (91 + 7)/2 = 49 cm