__Example__:*f* (*x*)=4-*x*^{2}

** Click** the "Graph" button
(this button also refreshes the graph).

** Enter** the endpoints of the interval [

**Example:**
[

** Click** the "+" and
"-"
buttons under the label marked "n="
to change the number of subintervals used for the approximation.

__Example__:*n*=8

** Adjust** the slider to determine which point in each
subinterval is used to
determine the height of the rectangle, from left endpoint to right endpoint.

**Example:** left endpoint

** To erase** the graph and all input fields, setting the
slider to a default position and

[

__Exponential__:

*f* (*x*)=*e ^{2}*

[

__Trigonometric__:

*f* (*x*) = sin *x*

[*a*,*b*]=[0,3.14159]

*n*=6 for both

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