Question

if sin20=0.34 find cos70​

Answer 1

Before we solve the problem, let us know some trigonometric formulae first :

• sin(90° - θ) = cosθ
• cos(90° - θ) = sinθ
• sin(180° - θ) = sinθ
• cos(180° - θ) = - cosθ

Given : sin20° = 0.34

To find : cos70° = ?

We solve the problem here :

Given sin20° = 0.34

or, sin(90° - 70°) = 0.34

or, cos70° = 0.34, since sin(90° - θ) = cosθ

Therefore, cos70° = 0.34 .