What is the value of -dr?

If r = [ 2 phi +cos^2(2phi+pi//4)]^(1//2) , then what is the value of the derivative of dr// dphi at phi = pi//4 ?

What is the value of int_0^1sin^2tdt+int_0^1cos^2tdt-int_0^1dr ?

What is the application of the satelite INSAT 3DR?

What was the claim to fame of Dr. Dwarka Nath Kotnis?

What are the DR's of a vector parallel to (2,-1,1) and (3,4,-1)