tanα=7cosβ=2√5/5tanβ = √5/(2√5) =1/2tan2β = 2tanβ/[ 1- (tanβ)^2]=1/( 1 - 1/4)=4/3tan(α+2β)=(tanα+tan2β)/( 1- tanα.tan2β)=( 7 + 4/3) /[ 1 - (7)(4/3) ]=( 25/3)/( -25/3)=-1α+2β = 3π/4
