\(a,VT=\left(\sin^252^0+\cos^252^0\right)-\left(\tan37^0-\tan37^0\right)+\dfrac{\tan42^0}{\tan42^0}=1-0+1=2=VP\\ c,VT=\dfrac{2\cos^2\alpha-\sin^2\alpha-\cos^2\alpha}{\sin\alpha+\cos\alpha}=\dfrac{\cos^2\alpha-\sin^2\alpha}{\sin\alpha+\cos\alpha}\\ =\dfrac{\left(\sin\alpha+\cos\alpha\right)\left(\cos\alpha-\sin\alpha\right)}{\cos\alpha+\sin\alpha}=\cos\alpha-\sin\alpha=VP\)
\(b,VT=\cos^2\alpha+\cos^2\alpha\cdot\dfrac{\sin^2\alpha}{\cos^2\alpha}=\cos^2\alpha+\sin^2\alpha=1=VP\\ d,VT=\sin^2\alpha+\left(1-\cos^2\alpha\right)\dfrac{\sin^2\alpha}{\cos^2\alpha}=\sin^2\alpha+\dfrac{\sin^2\alpha}{\cos^2\alpha}-\sin^2\alpha\\ =\dfrac{\sin^2\alpha}{\cos^2\alpha}=\tan^2\alpha=VP\)
