Find 
, when
If 
and 
prove that 
as 
Differentiating it with respect to t,
……(1)
And 
Differentiating it with respect to t,
……(2)
Dividing equation (2) by (1),
17
Find , when
If and prove that
as
Differentiating it with respect to t,
……(1)
And
Differentiating it with respect to t,
……(2)
Dividing equation (2) by (1),