Question

if tan theta is equal to 20/21, cos theta will be

Answer 1

tan a=20/21
tan^2 a=400/441
1+tan^2 a=841/441
sec a=29/21
cos a=21/29

Answer 2

Answer:

If Tan∅ is equal to 20/21,

Cos ∅ = 21/29

Step-by-step explanation:

Let x be the side of the hypotenuse.

By applying Pythagoras theorem, In a triangle ABC, if AC is hypotenuse, AB be the side opposite to theta and BC be the adjacent side of theta, then

AC² = AB² + BC²

x² = (20)² + (21)²

x² = 400 +441

x² = 841

⇒x=29 =AC

Sin∅ = AB /AC =20/29

Cos∅ = BC/AC =21/29

Therefore Cos∅=21/29