Question

What is the area of the region enclosed by the graphs of $y=e^x-2$, $y=\sin x$, and $x=0$ ?

Original question: What is the area of the region enclosed by the graphs of y=ex2y=e^x-2, y=sinxy=\sin x, and x=0x=0 ?

A 0.239 B 0.506 C 0.745 D 2.340 E 3.472

Expert Verified Solution

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Key concept: To find the enclosed area, identify the intersection point of the two curves and integrate the top function minus the bottom function.

Step by step

We want the area enclosed by

y=ex2,y=sinx,x=0.y=e^x-2, \quad y=\sin x, \quad x=0.

Step 1: Find the intersection point

The curves meet where

ex2=sinx.e^x-2=\sin x.

This equation has a solution between 00 and 11. Let that intersection be at x=ax=a.

Step 2: Determine which curve is on top

For xx between 00 and aa, the sine curve is above the exponential curve, so the area is

A=0a(sinx(ex2))dx.A=\int_0^a \left(\sin x-(e^x-2)\right)dx.

That is

A=0a(sinxex+2)dx.A=\int_0^a (\sin x-e^x+2)\,dx.

Step 3: Integrate

A=[cosxex+2x]0a.A=\left[-\cos x-e^x+2x\right]_0^a.

So

= -\cos a-e^a+2a+2.$$ Using the intersection value numerically gives $$A\approx 0.745.$$ Therefore, the area is $$\boxed{0.745}$$ which is choice **C**. ### Pitfall alert A common mistake is to integrate from $0$ to a guessed endpoint without first locating the intersection of the two curves. Another error is reversing top and bottom, which would make the area negative before taking the absolute value. ### Try different conditions If the vertical line $x=0$ were replaced by another boundary such as $x=c$, then the limits of integration would change accordingly. The same method still applies: find where the curves intersect and subtract bottom from top over the bounded interval. ### Further reading area between curves, intersection point, definite integral

FAQ

How do you set up the area integral?

Find the intersection of y=e^x-2 and y=sin x, then integrate the top curve minus the bottom curve from x=0 to the intersection point.

What is the area of the region?

The area is approximately 0.745 square units.

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