# Thread: Calculating the height of a triangle - isosceles

1. ## Calculating the height of a triangle - isosceles

Hello all,

I've been out of high school for many years and just started Trigonomtry and cannot fiqure out this problem to save my life. I would appreciate any help. Thank you in advance

In isosceles (picture a triangle)ABC, AB +AC, (picture a angle)C = 70 degrees, and BC = 4.0 cm.
calculate the height of the triangle to the nearest millimetre

Does anyone have any ideas?

I fiqured out the problem: 70 TAN = 2.7474 X 2 = 5.5 to the nearest millimetre. Apparently there's two right angles in an isosceles. Thanks anyways

2. Originally Posted by Amry
Hello all,

I've been out of high school for many years and just started Trigonomtry and cannot fiqure out this problem to save my life. I would appreciate any help. Thank you in advance

In isosceles (picture a triangle)ABC, AB +AC, (picture a angle)C = 70 degrees, and BC = 4.0 cm.
calculate the height of the triangle to the nearest millimetre

Does anyone have any ideas?

I fiqured out the problem: 70 TAN = 2.7474 X 2 = 5.5 to the nearest millimetre. Apparently there's two right angles in an isosceles. Thanks anyways
Hi Amry,

You may have figured out the answer, but your last statement is worded incorrectly. I think you meant to say that the altitude drawn from the vertex angle is perpendicular to the base, thus forming 2 right angles. But they're not in the same triangle. You split the isosceles triangle into 2 congruent right triangles.