Back to main page Triangle given two sides and included angle (SAS)
Printable instructions worksheet.
After doing this Your work should look like this

Start with two line segments and the included angle.

1.  Mark a point A that will be one vertex of the new triangle.
2.  Draw a ray from point A. This will become the side AB of the new triangle, so make it longer than AB.
3.  Set the compass width to the length of the given side AB.
4.  Set the compass on A, and mark a point B on the ray just drawn.
5.  With the compass set to any convenient width, from the point A on the given angle, draw an arc across both lines..
6.  Without changing the compass width, draw a similar sized arc at point A on the new triangle.
7.  Set the compass to the arc width at the given angle A. This the distance between the points where the arc intersects the sides of the angle.
8.  Make a similar arc on the new triangle so it crosses the previous arc.
9.  Draw a ray from A, through where the arcs intersect and onwards. This will become side AC of the triangle so make it longer than AC.
10.  Set the compass width to the distance AC.
11.  With the compass on A, make an arc across the second ray, creating point C.
12.  Draw the line BC, the third side of the triangle
Done, the triangle ABC has the desired two side lengths and included angle.