Activity-trigonometry problems

=Problem-1= prove that $$\frac{1-\tan^2 A}{1+\tan^2 A}=1-\sin^2 A$$

Interpretation of problems

 * 1) It is to prove the problem  based on trigonometric identities
 * 2) the function of one trigonometric ratio is relates to other

Concept development
Develop the skill of proving problem based trigonometric identity

Skill development
Problem solving

Pre Knowledge require

 * 1) Idea about trignometric ratios
 * 2) Idea about trignometric identities

Methos
When A=60° LHS=$$\frac{1-\tan^2 60°}{1+\tan^2 60°}$$ =$$\frac{1-{(\sqrt{3})}^2 }{1+{(\sqrt{3})}^2 }$$ =$$\frac{1-3}{1+3}$$ =$$\frac{-2}{4}$$ =$$\frac{-1}{2}$$-(1)
 * 1) Generalisation By Verification