How do I figure out the measures of these angles in an isosceles triangle?

Question

I am only given the fact that there is a 20 degree angle on top and of course both sides are equal because of the marks. The base doesn't have a number indicating what degree it is. :o(

Answer 1

180 - 20

160/2

80, 80, 20

Answer 2

All the angles of a triangle add up to 180 deg.
The top is 20 and the other two angles are the same because the angles are congruent angles so you have 180 -20 = 160/2 =80
You get a 20, 80, 80 isosceles triangle.

Answer 3

Remember that the sum of all 3 angles in a triangle are equal to the sum of 2 right angles. This means that on a plane, like your paper, the sum of angles in your triangle is 90 degrees + 90 degrees, or 180 degrees. So, 180 - 20 = 160 degrees left in the triangle after you subtract away the 20 degrees you were given. Since 160/2 = 80, your three angles are 80, 20, and 80 degrees.

Answer 4

What you need to realize to solve this problem is the 2 angles opposite the 2 equal sides are equal. There are 180* in the triangle so:

180 = 20 + 2x

160 = 2x

x= 80

It is a 20-80-80 triangle.

Answer 5

All the interior angles of a triangle sum to 180°. Referring to the angles as A, B, and C,

A + B + C = 180­°

Since the "two" angles are equal, B = C:

A + 2B = 180°

Since A = 20°,

(20) + 2B = 180°
2B = 160°
B = C = 80°