Posted by **SL** on Wednesday, June 30, 2010 at 7:42pm.

the base of an isosceles triangle is 18 centimeters long. The altitude to the base is 12 centimeters long. What is the approximate measure of a base angle of the triangle?

- geometry -
**drwls**, Wednesday, June 30, 2010 at 8:03pm
Since it is isosceles, the altitude splits it into two congruent right triangles. The base angle is

arctan(12/9) = arctan(4/3). It's a "3,4,5" right triangle. Use a table or calculator to get the angle. It's about 53 degrees

- geometry -
**Henry**, Wednesday, June 30, 2010 at 8:07pm
The altitude of an isosceles triangle

is the perpindicular bisector of the

base and devides the triangle into 2

congruent rt. triangles. Y=12=altitude, X=18/2=9= 1/2 of base.

TanB=Y/X=12/9=1.3333, B=53.13 Degrees.

## Answer this Question

## Related Questions

- Euclidean Geometry - I am in the 10th Grade and my question is: The base of an ...
- Math - The altitude of a triangle is increasing at a rate of 2500 centimeters/...
- CAL - The altitude of a triangle is increasing at a rate of 2500 centimeters/...
- CAL - The altitude of a triangle is increasing at a rate of 2500 centimeters/...
- Calculus Please help! - The altitude of a triangle is increasing at a rate of ...
- calculus - The altitude of a triangle is increasing at a rate of 3.000 ...
- geometry - Each base of an isosceles triangle measures 42 degrees, 30'. The base...
- Algebra 1 - A right triangle has a base measuring 5 centimeters & a height of 12...
- geometry - how long are the congruent legs of isosceles triangle if its base ...
- geometry - how long are the congruent legs of isosceles triangle if its base ...