Calculate All Angles in an Isosceles Triangle with 70° Vertex Angle

Question

Find all the angles of the isosceles triangle using the data in the figure.

00:00 Find the angles of the triangle

00:03 The sum of angles in a triangle equals 180

00:06 Subtract the known angle from this sum

00:09 This is the sum of the remaining angles

00:12 Divide by 2 because they are equal (isosceles triangle)

00:16 And this is the solution to the problem

Let's remember that in an isosceles triangle, the base angles are equal to each other.

In other words:

$C=B$

Since we are given the vertex angle, which is equal to 70 degrees, we'll recall that the sum of angles in a triangle is equal to 180 degrees.

Now let's find the base angles in the following way:

$180-70=110$

$110:2=55$

Therefore, the angle values in the triangle are: 55, 55, 70

70, 55, 55