Answer:
The measure of third angle is 40°
B is correct.
Step-by-step explanation:
Mark is making a decoration for a rally, using a string of triangular strips. Each strip is an isosceles triangle when flattened out.
In figure, we are given the base angle is 70°
For isosceles triangle base angles are equal.
Two angle of a isosceles triangle are 70° and 70°
Let third angle of triangular strips be A
Using angle sum property of triangle ( sum of all three angles of a triangle is 180°)
A+70°+70°=180°
A=180-140 = 40°
Hence, The measure of third angle is 40°