Question
If cos (40° + x) = sin 30° the value of x is
-
30°
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40°
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20°
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60°
Solution
C.
20°Tips: -
cos (40 + x) = sin 30° = sin (90° – 60°) ⇒ cos (40° + x) = cos 60° ⇒ x = 20°.
