Remote, Exterior And Interior Angles Of A Triangle - Math Warehouse

Interactive Demonstration of Remote and Exterior Angles

The interactive program below allows you to drag the points of the triangle around. Notice that the sum of the remote interior angles (C and D) equal the measure of exterior angle A.

∠ C = ∠ D = ∠ A = Choose Remote Angles C and D C and B B and D Share this Graph Copy Sharing Link Embed In Your Website Drag Points Of The Triangle To Start Demonstration

Practice Problems

Problem 1

Use the formulas described on this page to calculate the values of x (a remote interior angle) and of Y.

Show Answer

Since X and, $$ \angle J $$ are remote interior angles in relation to the 120° angle, you can use the formula.

$$ 120° = 45° + x \\ 120° - 45° = x \\ 75° = x. $$

Now, since the sum of all interior angles of a triangle is 180°. You can solve for Y.

$$ 75° + 45° + y = 180° \\ 120° + Y = 180° \\ Y = 60° $$