Question

how we can remember trignometric formulae and what is d formulae for converse of pythagorus theorem

Answer 1

you can remember then either by memorizing or by practicing several times. 

Answer 2

hi mate,

Proof: Construct another triangle, △EGF, such as AC = EG = b and BC = FG = a.

In △EGF, by Pythagoras Theorem:

EF²= EG2 + FG² = b² + a²…………(1)

In △ABC, by Pythagoras Theorem:

AB² = AC² + BC²= b² + a² …………(2)

From equation (1) and (2), we have;

EF² = AB²

EF = AB

⇒ △ ACB ≅ △EGF (By SSS postulate)

⇒ ∠G is right angle

Thus, △EGF is a right triangle.

Hence, we can say that the converse of Pythagorean theorem also holds.

Hence Proved.

i hope it helps you.