3points
the measure of the vertex angle of an isosceles triangle is 120 degrees. what is the measure of the base angle?
o 30 degrees
0 40 degrees
o 35 degrees
o 60 degrees

a) The measure of the base angle is  30°.

Step-by-step explanation:

The angle formed by the vertex of two equal sides in an isosceles triangle is called a VERTEX ANGLE.

Also, the other two base angles are equals they are opposite to equal sides.

Now, let us assume that the base angle = a

So, by ANGLE SUM PROPERTY:

Sum of all angles of  triangle = 180°

⇒ 120° + a  +  a = 180°

or, 2 a = 180 -120  = 60°

or, a   = 60/2  = 30°

or, a  = 30°

Hence, the measure of the base angle is  30°.

step-by-step explanation:

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12

step-by-step explanation:

a triangle's   full angle is 180 degrees so 180 - 156 = 24. 24/2=12