Posted by **Blake** on Saturday, April 28, 2007 at 6:16pm.

I am in the 10th Grade and my question is: The base of an isosceles triangle is 21cm. long. The altitude to the base is 9cm. long. What is the approx. measure of a base angle of the triangle?

The tangent of that angle is 9/10.5 = 0.8571

Trigonometric tables will tell you that the angle is 40.6 degrees.

How did you get 9/10.5 from the problem?

Never mind I got it now. Thanks for the help!!!