CPM Homework Help : CC2MN Problem 4-142

If each triangle below is drawn accurately, identify whether it is an obtuse, acute, or right triangle. Name the angle or angles that helped you to decide.

Hint (a):
Examine all three angles of the triangle.
Is the measure of any of the angles greater than or equal to $90°$ ?
Answer (a):
$m\angle C$ is greater than $90°$ , so this figure is an obtuse triangle.

Hint (b):
See part (a).
Answer (b):
Since all the angles measure less than $90°$ , the figure is an acute triangle.

Hint (c):
What does the box on angle Y mean?
More help (c):
The box means that the angle at that point is a right angle.
How can you identify this triangle?

Hint (d):
See part (a).