# Thread: value of x in an isosceles triangle

1. ## value of x in an isosceles triangle

hi,this is my question:

triangle ABC is isosceles.
one angle is x.
another angle is 4x.

find the two possible values of x.

im unsure how to work this out, i know that in an isosceles triangle 2 angles are equal.

could someone tell me how to work this question out please?

thanks!

2. Let's say we have angles A, B, and C.
You know that two of them are x and 4x.
So let's say that A is the one that is x, and B is the one that is 4x. It doesn't matter which we choose (mathematicians use the phrase "without loss of generality" before making such assumptions, FYI).

So we have A + B + C = 180. What is C? Well, since it's an isosceles triangle, C must equal one of the other two. C must equal x OR C must equal 4x.
Then A + B + C = 180 becomes
x + 4x + x = 180. Solve for x.

Second case: C = 4x
Then A + B + C = 180 becomes
x + 4x + 4x = 180. Solve for x.

Those are your two values for x!

,

,

,

,

,

### find the value of x isosceles triangle

Click on a term to search for related topics.