Answer:
x = 40°
Step-by-step explanation:
In order to answer this problem, you will need to know the definition of an isosceles triangle.
An Isosceles triangle is specified as a triangle with 2 of its 3 sides having equal lengths.
Step 1: Draw your triangle.
Since 2 of your 3 sides are equal length and the primary angle measures 100°, you are dealing with an obtuse triangle or, properly named, a obtuse isosceles triangle.
Step 2: Label your angles inside of your triangle.
Remember that the sum of the angles inside of a triangle must add up to equal 180°.
Since we know the triangle we are dealing with in this problem, we can label our unknown angles 'x'.
Caution: The above statement ONLY applies to this type of triangle.
Step 3: Write an equation.
100° + x° + x° = 180°
Step 4: Solve for x.
100° + x° + x° = 180°
100° + 2x° = 180°
2x = 80°
x = 40°
