Similar Polygon Help

Subject Areas

Tools / Misc

bCalc

drag-N-drop

scrnGC2: Calc Input

scrnGC3: f(x) Plot Input

scrnGC4: g(x) Plot Input

The inputs above will be hidden when the program finally gets launched. Currently, I am not hiding them even when you close the calculator. The purpose of the inputs is to help in debugging. This allows you to enter simple code on the calculator screen but the program translates the input to javascript math. Give it a try and see if you notice any obvious problems or have suggestions for improvements.

gCalc

drag-N-drop

Select precision* of answer:

Select angle mode:

Enter expression to evaluate here:

The answer is shown below:

Enter function to be plotted:

f(x) =

Enter 2nd function, if needed:

g(x) =

Change or reset the x-y scaling below:

x_min =

x_max =

y_min =

y_max =

Accuracy Disclaimer

The javascript math object methods used for this calculator are not accurate for very large or very small numbers. In particular, the trigonometric functions may yield very small answers that should actually be zero or very large answers that should be infinite. This typically occurs at 90� or pi/2 intervals.

DO NOT USE WHERE HIGH PRECISION IS REQUIRED. USE AT YOUR OWN RISK.

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Similar Polygon Help

To enlarge or reduce the size of a polygon, you must first determine the scale factor.

If you are reducing the size, the scale factor will be less than one (1).

If you are enlarging the size, the scale factor will be greater than one (1).

Be careful to note whether you are going from large-to-small or small-to-large.

The scale factor is determined by finding 2 similar sides where the length is given.

Example 1:

Given: PQ = 3 QR = 2 RS = 3 SP = 5

If: WZ = 10

Then: Scale Factor = WZ/SP = 2

WX = 6 XY = 4 YZ = 6

Note how each side was twice the size of the smaller polygon.

For the triangles shown below, you follow the same procedure outlined above but be careful that you account for the total length of the sides of the larger triangle, especially where they overlap.

Example 2:

Given: AB = 8 AD = 12 BE = 7.5

If: CD = 8

Then: Scale Factor = CD/(AD+CD) = 8/20 = 0.4

DE = 0.4(AB) = 0.4(8) = 3.2

EC = 0.4(BE+EC) = 0.4(7.5+EC) = 3+0.4(EC)

0.6(EC) = 3

EC = 3/0.6 = 5

Note how each side was four tenths the size of the larger triangle.