Copy An Angle

For the copy a triangle tool, select five things: 1) The destination vertex, 2) Another point on the line that the destination vertex is on to set the direction of the side of the triangle copy, 3,4,5) the vertices of the triangle to copy. Put the vertex you want to go on the destination vertex in the middle. You might have to do it in the reverse order if it doesn't work out right. Use the angle measurement tool to measure the new angle. Click on the vertex as the second of the three points to measure the angle.