Sunday 30 October 2011

Trigonometry-1 (XAT-2011) (3-Marks)

What is the maximum possible value of 21Sinx+72Cosx?
(1)21   (2) 57   (3) 63   (4) 75   (5) None of these
Solution follows here:
Solution:
It is a direct trigonometric formula based one.
Maximum value of aSinx+bCosx = √(a2+b2)
√(a2+b2) = √(212+722) = √(32 72+32 242) = 3 √(72+242)
= 3 √(49+576) = 3 √625 = 3*25 = 75
Answer (4)

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