If cos \(\theta\) = x and sin 60 o = x + 0.5 0 o

MATHEMATICS
WAEC 2016

If cos \(\theta\) = x and sin 60o = x + 0.5 0o < \(\theta\) < 90o, find, correct to the nearest degree, the value of \(\theta\)

  • A. 32o
  • B. 40o
  • C. 60o
  • D. 69o

Correct Answer: D. 69o

Explanation

sin 60o = x + 0.5 0o(given)

0.8660 = x + 0.5

0.8660 - 0.5 = x

x = 0.3660

cos\(\theta\) = x(given)

cos\(\theta\) = 0.3660

Hence, \(\theta\) = cos-1(0.3660)

= 68.53o

= 69o (nearest degree)



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