Posted by **Kaiden** on Sunday, September 18, 2011 at 12:51am.

Suppose that f and g are two functions both continuous on the

interval [a, b], and such that f(a) = g(b) = p and f(b) = g(a) = q

where p does not equal to q. Sketch typical graphs of two such functions . Then apply the intermediate value theorem to the function

h(x) = f(x) - g(x) to show that f(c) = g(c) at some point c of

(a, b).

- Calculus I -
**MathMate**, Sunday, September 18, 2011 at 8:41am
An example case is illustrated by the sin(x) and cos(x) functions between π/2 and 2π (see link at end of post).

"Intermediate value theorem":

"for each value between the least upper bound and greatest lower bound of the image of a continuous function there is at least one point in its domain that the function maps to that value".

Since p≠q, either p>q or q>p. Assume p>q, b>a.

Then f(a)>g(a), and f(b)<g(b), so if

h(x)=f(x)-g(x)

then h(a)>0, and h(b)<0.

You will need to prove, using the intermediate value theorem, that h(x0)=0 at some point a<x0<b.

Proof is similar when p<q.

http://imageshack.us/photo/my-images/821/1316321469.png/

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