yes u r absolutely right.But please explain me how

At 25⁰C ,benzene and toulene have densities 0.879 and 0.867 g/cc respectively.Assuming that benzene-Toulene solutions are ideal , establish the equation for the density of the solution

 

d=1/100(0.879V+0.867(100-V))

 

where V is the volume percent of benzene.

If a,b,c and k are constant quantities and  ,, are variable subjects to the relation a tan alpha+btan beta+c tan gama=k,find the minimum value of

 

tan²alpha+tan²beta+tan²gama