Mellonie said:
Without using a calculator show that tan(inverse)3/5 + Tan(inverse)1/5 = Pie/4
Let a = tan(inverse)3/5 and b = Tan(inverse)1/5
Then take tan of LHS of equation above:
tan(a=b)
= (tana + tanb)/1 - tanatanb
Remember tantan(inverse)3/5 = 3/5, and similarly tanTan(inverse)1/5 = 1/5
so ... = 3/5 + 1/5 / (1 - 3/5.1.5)
= 1
= RHS
