# Trigo

• Q42
Pls explain their sol from line 1 how could they write 1st line and further

• @abcd
They hav used half angle formulae:

$tan(A/2)=\sqrt{\frac{(s-b)(s-c)}{s(s-a)}}$

Then multiplied and divided by $\sqrt{s(s-a)}$

Then Heron's formula.

Looks like your connection to dubbtr was lost, please wait while we try to reconnect.