This triangle can be classified as an Acute Scalene Triangle.
It is an Acute triangle because all of its sides are acute (less than 90 degrees)
It is a Scalene triangle because all of its sides are of different lengths.
To find the missing angle degree we must subtract 61 and 78 from 180. We subtract them from 180 because all angles of a triangle add up to 180 degrees.
180 - 61 - 78 = 41.
So the missing angle (x) = 41 degrees.
Hope I helped!
