If the three vectors `veca,vecb,vecc` are such that `veca+vecb+vecc=vec0' and

If the three vectors `veca,vecb,vecc` are such that `veca+vecb+vecc=vec0" and " |veca|=3,|vecb|=4,|vecc|=5`, then show that `veca*vecb+vecb*vecc+vecc*veca=-25`.