If the matrix `[(1,3,lamda+2),(2,4,8),(3,5,10)]` is singular then find `lamda`

Assertion (A) : If the matrix A=[{:(1,3,lambda+2),(2,4,8),(3,5,10):}] is singular , then lambda=4 . Reason (R ) : If A is a singular matrix, then |A|=0

If the matrix A=[(8,-6,2),(-6,7,-4),(2,-4,lamda)] is singular one, then lamda is

I: If the matrix A =[(8,-6,2),(-6,7,-4),(2,-4,lamda)] is singular one, then lamda=3 II: If the matrix [(cos theta, sin theta, 0),(sin theta, cos theta, 0),(0,0,1)] is singular then theta=pi//2

The matrix A=[(2,lamda,-4),(-1,3,4),(1,-2,-3)] is a non-singular, if