Sec A = Cosec B = 15/7, then find the value of A+B.
Asked by | 20th Aug, 2011, 01:58: AM
Expert Answer:
secA = Cosec B = 15/7
So, cos A = sin B = 7/15
sin A = { 1 - cos2 A }1/2 = { 1 - (15/7)2} 1/2 = ?176 / 15
cos B = { 1 - sin2 B } 1/2 = { 1 - (15/7)2} 1/2 = ?176 / 15
Now, sin ( A + B ) = sin A cos B + cos A sin B
= ?176 / 15 . ?176 / 15 + 7/15 . 7/15
= 176/225 + 49 / 225
= 225/ 225 = 1
sin ( A+B) = 1 = sin 90o
A + B = 90o
Hence , toe correct answer is option (3)
Answered by | 20th Aug, 2011, 04:34: PM
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