The degree measure of the vertex angle of an isosceles triangle is 120. Find the measure of a base angle of the triangle.
what do you have to do?
and Thank you
2007-08-09 09:24:43 · 5 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
You need to know that an isosceles triangle has congruent side lengths and angles. You also need to know that the sum of all angles in a triangle is 180 degrees.
With this information we can make the following equation.
120 + x + x = 180
120 + 2x = 180
2x = 60
x=30
30 degrees are the base angles' of the triangle.
Good luck.
2007-08-09 09:27:49 · answer #1 · answered by de4th 4 · 0⤊ 2⤋
The sum of the measures of the three angles in a triangle is always 180. In an isoceles triangle, the two base angles are congruent. Therefore, if we are given the vertex angle, the two base angles both have measure x, the only unknown. And since the sum of all three angles must be 180, we can say 120 + x + x = 180. This is easy to solve, and gives you a result of x = 30. Each base angle has measure 30 degrees.
2007-08-09 16:29:01 · answer #2 · answered by DavidK93 7 · 0⤊ 0⤋
well from standard maths that you learn in school. you know that the angles at the base of an isosceles triangle are equal. so if the verex is 120
180 - 120 = 2*x
60 = 2*x
x = 30
2007-08-09 16:34:00 · answer #3 · answered by tom t 2 · 0⤊ 0⤋
the Degrees of a triangle always equal 180 degrees
if 120 already has been used and you know the other two are equal, then... 180-120=60/2= 30
120 30 30
2007-08-09 16:29:04 · answer #4 · answered by Phish 2 · 0⤊ 0⤋
120 + x + x = 180
x = 30
2007-08-09 16:27:39 · answer #5 · answered by fcas80 7 · 0⤊ 0⤋