Question

lesson 7: triangles
classifying triangles by angle measurement
by definition, an acute triangle has ______
\ta. one angle greater than 180 degrees
\tb. all angles less than 90 degrees
\tc. one angle greater than 90 degrees
\td. one angle equal to 90 degrees

Explanation:

To determine the correct option for the definition of an acute triangle, we analyze each choice:

• Option a: A triangle's interior angles sum to 180°, so no angle can be greater than 180°, eliminating a.
• Option b: By definition, an acute triangle has all three interior angles measuring less than 90° (acute angles).
• Option c: A triangle with one angle greater than 90° is an obtuse triangle, not acute, so c is incorrect.
• Option d: A triangle with one angle equal to 90° is a right triangle, not acute, so d is incorrect.

Answer:

b. all angles less than 90 degrees