If y= tanx, x=pi, and dx= .5, what does dy equal?

Question

a)-.25
b) -.5
c) 0
d).5
e).25

Answer 1

if y = tanx
dy/dx = sec^2 x

if dx=.5 and x=π

dy/.5 = sec^2 π , ------ (cosπ = -1, so secπ = -1)
dy = .5(-1)^2 = .5