If you flip the 30-60-90 triangles so they look similar, and find the difference between the length of 60, and the length of 40.
40÷60 =.6666 etc
You can prove this by plugging in 60 •.66666 = 39.9999 or about 40.
The triangle I started with had a length of 60, so just used the tangent of 60° to find the adjacent. Since we know the relationship of the triangles, Multiply your answer, 103.923 •.666666 Which equals 69.2819 69.2819 is the length of the 40 triangle.
