Question

Sin thita = m2 - n2 / m2+ n2 find ten thita

Answer 1

as we know,

sin thita = opposite/ hypotenuse

then, here given
opposite = m2 - n2
hypotenuse = m2 + n2

adjacent = √{(m2 + n2)^2 - (m2 - n2)^2}
= √{(m2 + n2 + m2 - n2) (m2+n2 - m2 + n2)}
= √{(m2 + m2) (n2 + n2)}
=√{4m^2 n^2}
=√{(2mn)^2}
=2mn

hence,
tan thita = opposite/ adjacent
=( m2 -n2) / 2mn

I hope this will help you......