Which set of angles can form a triangle?
A: 2 acute and 1 right
B: 1 acute and 2 obtuse
C: 1 acute and 2 right
D: 1 acute, 1 right and 1 obtuse
Answer: A: 2 acute and 1 right
The key to triangle formation is to have the aggregate of three angles equaling 180 degrees. Mixing two the acute angular solids (less than 90 degrees each) and one of 90 degrees right angles completes this requirement. An acute triangle can be as small as 0 degrees in one angle or as big as 90 degrees in one angle, and in the right triangle there must exist a right angle which together with the other two will sum up to exactly 90 degrees thus making the total sum of the angles equal to 180 degrees, which is a needed condition for the triangle to conform. The other choices given will either have angles that add up to over 180 degrees or indivisible parts that are impossible for a triangle.