00:01
The sum of the measures of any angles of a triangle are 180 degrees.
00:05
So in triangle a, b, c, the measure of angle a plus the measure of angle b plus the measure of angle c equals 180.
00:12
In triangle a, b, angles a and b have the same measure, so angle a equals angle b.
00:19
And angle c is 60 degrees greater than each of angles a and b.
00:23
So angle a plus 60 equals angle c.
00:28
So now we can use substitution.
00:31
Angle a equals b, so i'm going to plug in b here.
00:36
Actually, we're going to leave that as angle a, plus angle b equals angle a, so i'm going to plug in a here.
00:42
And angle c, we're going to substitute in a plus 60...