If 
show that 
Given : 
To show : 
Formula used :
Where cij = ai1b1j + ai2b2j + ai3b3j + ……………… + ainbnj
If A is a matrix of order a 
b and B is a matrix of order c 
d ,then matrix AB exists and is of order a 
d ,if and only if b = c
A = 
A2 = 
× 
A2 = 
A2 = 
We know that cos2α = 
and sin2α = 
A2 = 
A2 = 
1