If A is an acute angle and cot A + cosec A = 3, then the value of cos A is equal to:
Answer & explanation
Correct answer: option 1
cot A + cosec A = 3 -------(1)
We know ,
cosec A - cot A = \(\frac{1 }{cot A + cosec A }\) = \(\frac{1 }{3 }\) -----(2)
Adding equation 1 and 2.
2 cosecA = 3 + \(\frac{1 }{3 }\) = \(\frac{10 }{3 }\)
cosecA = \(\frac{5}{3 }\)
H² = P² + B²
5² = 3² + B²
B = 4
Now ,
cosA = \(\frac{B}{H}\) = \(\frac{4}{5 }\)