The area of the region {(x,y):∣x−1∣≤y≤5−x2} is equal to :
(A)25sin−1(53)−21
(B)45π−23
(C)43π+23
(D)45π−21✓ Correct
Answer: (D)
Solution
The region is bounded below by y=∣x−1∣ and above by the circle x2+y2=5. The curves intersect when (x−1)2=5−x2, giving x2−x−2=0, so x=2 or x=−1.
The region consists of triangle ABC (vertices at (1,0), (2,1), (-1,2)) plus the circular segment BCD. The triangle has area 21∣1(1−2)+2(2−0)+(−1)(0−1)∣=21∣−1+4+1∣=2.
The circular segment from x=−1 to x=2 on the circle x2+y2=5 (upper half) has area equal to a quarter circle minus a triangle: 4π(5)2−21(5)2=45π−25.
Total area = 2+45π−25=45π−21.
JEE Main · 2022 · 29 Jul 2022 · Shift 1 · Single correct option