`#tnvt`
`A=\frac{tan78^0}{cot12^0}-sin^2 54^0-sin^2 36^0`
`=\frac{tan78^0}{tan(90^0-12^0)}-(sin^2 54^0+sin^2 36^0)`
`=\frac{tan78^0}{tan78^0}-[sin^2 54^0+cos^2(90^0-36^0)]`
`=1-(sin^2 54^0+cos^2 54^0)`
`=1-1`
`=0`
`B=tan46^0 .tan44^0+\frac{1-sin^2 42^0}{sin^2 48^0}`
`=tan46^0 .cot(90^0-44^0)+\frac{(sin^2 42^0+cos^2 42^0)-sin^2 42^0}{cos^2(90^0-48^0)}`
`=tan46^0 .cot46^0+\frac{sin^2 42^0 +cos^2 42^0 -sin^2 42^0}{cos^2 42^0}`
`=1+\frac{cos^2 42^0}{cos^2 42^0}`
`=1+1`
`=2`
