Can you recommend an online angle calculator for determining the needed lengths of three lines to create a certain angle among them? The ones I saw from a basic google search seemed like they were asking for more information than I have.

I know of no calculator to do this, but what I can say is that the size of angles in a triangle add to 180.  This means if you know angle A and B, angle is found as 180 - A - B.

If we have a right triangle (one angle is 90 and the other two are acute), the sum of the two smaller angles is 90.

If we have angle A, and are given that angle B is twice A and that angle C is
three times the measure of A, then we have 2A + A + 3A = 180.
This gives A = 30, so the other angle is 2 times this, which is 120.

I believe the best way to do this is use Excel.
To do the calculations in Excel needs the angle be to 180.

If the angles are measured in radians, the sum of the three angles of a triangle is pi.

The correct formulas to use is given any triangle with sides a and b with an angle between them C,
then a + b - 2ab*cos(C)= C.


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Scott A Wilson


I can answer whatever questions you ask except how to trisect an angle. The ones I can answer include constructing parallel lines, dividing a line into n sections, bisecting an angle, splitting an angle in half, and almost anything else that is done in geometry.


I have been assisting people in Geometry since the 80's.

I have an MS at Oregon State and a BS at Oregon State, both with honors.

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I was the outstanding student in high school in the area of geometry and math in general.

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