CPM Homework Help : CC3 Problem 9-49

Use what you know about the angles in a triangle to find $x$ in each diagram below. Show all work. Then classify each triangle as acute, right, or obtuse.

Hint:

By the Angle Sum Theorem, the sum of all interior angles of a triangle is always $180º$ .

Step 1 (a):
$x + 40 + 80 = 180$
Step 2 (a):
$x + 120 = 180$
Partial Answer (a):
$x = 60°$

More Help (b):
$(2x) + (x + 12) + (96) = 180$