Using the principal values of the inverse trigonometric functions, the sum of the maximum and the minimum values of 16 ( ( -1x )2+ ( cosec-1x )2 ) is :
- 24 2
- 18 2
- 22 2
- 31 2
Answer
(3) 22 2
Solution
-1x+ cosec-1x= 2; let = -1x [0, ], 2.
f=16 [ 2+ ( 2- )2 ]=16 [2 ( - 4 )2+ 28 ], an upward parabola.
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Minimum at = 4: 2 2
Maximum at the farther end = : 20 2
Sum =22 2
Answer: (3)