Final answer:
To find the measure of angle a, set up an equation using the given information and solve for a. The measure of angle a is 45 degrees.
Step-by-step explanation:
To find the measure of angle a, let's set up an equation using the given information. We know that angle b is three times as large as angle a, so we can write b = 3a. We also know that the exterior angle at c measures 140 degrees, which means that the sum of angles a and b is equal to 180 degrees. Using these two equations, we can solve for a.
First, substitute b = 3a into the equation a + b = 180 and solve for a: a + 3a = 180. Combine like terms to get 4a = 180, then divide both sides by 4 to find that a = 45 degrees.
Therefore, the measure of angle a is 45 degrees.
Learn more about Angles in a circle