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!
Acute and scalene 61+78+n=180 139+n=180 -139= n= 41 degrees
here’s a link incase you have the rest of these problems i found it online. go down to page22 https://www.lcps.org/cms/lib/VA01000195/Centricity/Domain/2053/geometryreviewANSWERKEY.pdf
It's a half of an equilateral triangle because their angles measure 30° and 60° (an equilateral triangle has 3 angles of 60°) So x=(2h/√3)/2=h√3=27√3≈15.6
