Question

lesson 7: triangles
classifying triangles by angle measurement
by definition, a right triangle has ______
a. all angles less than 90 degrees
b. one angle greater than 180 degrees
c. one angle equal to 90 degrees
d. one angle greater than 90 degrees
check answer

Explanation:

To solve this, we recall the definition of a right triangle: a right triangle has one angle equal to 90 degrees (a right angle). Let's analyze each option:

• Option a: All angles less than 90 degrees describes an acute triangle, not a right triangle.
• Option b: A triangle cannot have an angle greater than 180 degrees (since the sum of angles in a triangle is 180 degrees), so this is impossible.
• Option c: By definition, a right triangle has one angle equal to 90 degrees. This matches the definition.
• Option d: One angle greater than 90 degrees describes an obtuse triangle, not a right triangle.

Answer:

c. one angle equal to 90 degrees