D because (5^2)= 25 + (12^2)=144 = 169. (13^2)=169. 25+144=169
It is probably B x has to be more than 7 but can be equal 7 at the same time.
721*8= 5768.................
The product of 4 and 5 is 20.
Step-by-step explanation:
L.H.S=(1-cosB)(1+cosB)
=(1-cos^2B). {using (a+b) (a-b)=(a^2-b^2)in second step}
=sin^2B
=1/cosec^2B
Therefore,L.H.S=R.H.S proved
