Question

which of these shapes is an acute scalene triangle?

Explanation:

An acute scalene triangle has all 3 angles less than 90° (acute) and all 3 sides of different lengths (scalene).

1. Red triangle: Appears to have one right/obtuse angle, so not acute.
2. Green triangle: Is isosceles (two equal sides), not scalene.
3. Bottom-left pink triangle: All angles are acute, and all sides appear to be different lengths, fitting the definition.
4. Bottom-right pink triangle: Has one obtuse angle, so not acute.

Answer:

The bottom-left pink triangle (the small, wide acute triangle with all sides of unequal length)