Question

for each triangle, check all that apply.
triangle a
triangle b
triangle c
triangle d
□scalene
□isosceles
□equilateral
□scalene
□isosceles
□equilateral
□scalene
□isosceles
□equilateral
□scalene
□isosceles
□equilateral

Explanation:

Step1: Classify Triangle A

All 3 sides equal ($9=9=9$). A triangle with 3 equal sides is equilateral, and all equilateral triangles are also isosceles (at least 2 equal sides).

Step2: Classify Triangle B

All angles are different ($90^\circ, 60^\circ, 30^\circ$), so all sides are different. A triangle with no equal sides is scalene.

Step3: Classify Triangle C

All 3 angles equal ($60^\circ=60^\circ=60^\circ$), so all sides are equal. This makes it equilateral, and also isosceles.

Step4: Classify Triangle D

2 sides equal ($6=6$), 1 side different (10). A triangle with exactly 2 equal sides is isosceles.

Answer:

• Triangle A: Isosceles, Equilateral
• Triangle B: Scalene
• Triangle C: Isosceles, Equilateral
• Triangle D: Isosceles