##### Geometry: 1,001 Practice Problems For Dummies (+ Free Online Practice)

In geometry, you can use the exterior angle of a triangle to find a missing interior angle. The following practice questions ask you to do just that, and then to apply some algebra, along with the properties of an exterior angle, to find a missing variable.

## Practice questions

Use the figure and the given information to answer the following questions.

1. In triangle WXY,

2. In triangle WXY,

Each angle is represented by the following:

Solve for the variable b.

1. 70 degrees

The exterior angle of a triangle is equal to the sum of the two nonadjacent interior angles of the triangle, so set up an equation and solve for x:

Plug in the value for x to find

2. 120 degrees

The exterior angle of a triangle is equal to the sum of the two nonadjacent interior angles of the triangle. Use this relationship to solve for a:

Plug in the value of a to find

The angles of a triangle add up to 180 degrees. Therefore,

Allen Ma and Amber Kuang are math teachers at John F. Kennedy High School in Bellmore, New York. Allen, who has taught geometry for 20 years, is the math team coach and a former honors math research coordinator. Amber has taught all levels of mathematics, from algebra to calculus, for the past 14 years.