Question

Proved that (cos40+x)=sin30

Answer 1

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→ Sine and Cosine are Complimentary Functions, i.e, cos( 90° - x ) = sin x

→ Utilizing the above relation, 
  • cos( 90° - ( 50° - x )) = sin 30°
=> sin( 50° - x ) = sin 30°

• Assuming x to be bound as : 0° ≤ x ≤ 90°

=> ( 50° - x ) = 30°
=>  x = ( 50° - 30° ) = 20°
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