we want the slopes to be equal
4cosx = x
That occurs only 3 places.
See
http://www.wolframalpha.com/input/?i=x+%3D+4cosx
For how many values of x will the tangent lines to y=4sinx and y=x^2/2 be parallel?
A. 0
B. 1
C. 3
D. 4
E. Infinite
Thanks.
1 answer