To find the measure of the exterior angle \( a \), we can use the property that the exterior angle of a polygon (in this case, a triangle) is equal to the sum of the two opposite interior angles.
Given the two interior angles of 35° each:
\[ a = 35° + 35° \]
Calculating this:
\[ a = 35° + 35° = 70° \]
Therefore, the measure of the exterior angle \( a \) is:
\[ a = 70° \]