A triangle where all angles are less than 90 degrees is called

A triangle where all angles are less than 90 degrees is called

• A. Equilateral triangle
• B. Isosceles triangle
• C. Right triangle
• D. Acute triangle

Answer: (D)

All three angles are less than 90 degrees, so every angle is acute. That makes the triangle an acute triangle. A right triangle, by contrast, has a 90-degree angle, which isn’t allowed here. The other terms describe sides—not angles—so while an equilateral or isosceles triangle can be acute, the appropriate label given the angle condition is acute triangle.

All three angles are less than 90 degrees, so every angle is acute. That makes the triangle an acute triangle. A right triangle, by contrast, has a 90-degree angle, which isn’t allowed here. The other terms describe sides—not angles—so while an equilateral or isosceles triangle can be acute, the appropriate label given the angle condition is acute triangle.