I started with the different quotient formula:Find the IRoC at the point (90 degrees, 5) on f(x) = 5sin(x)

IRoC = ( f(x+h) - f(x) ) / h , h-->0

=( 5 sin (90 +h) - 5 ) /h

= (5 sin h) / h

What do I do next?? I don't think I can factor out the h, even if I did what would sin take as an argument?

Thank you for the help.

Edit: Also, how would you apply the same formula with an exponential function like y = 100(0.85)^x , on x = 0 ??