Question

which of the following could be angle measures for a triangle? a 120°, 50°, 20° b 100°, 200°, 60° c 30°, 50°, 80° d 40°, 50°, 90°

Explanation:

Step1: Recall angle - sum property of a triangle

The sum of the interior angles of a triangle is always 180°.

Step2: Check option A

$120^{\circ}+50^{\circ}+20^{\circ}=190^{\circ}
eq180^{\circ}$

Step3: Check option B

$100^{\circ}+200^{\circ}+60^{\circ}=360^{\circ}
eq180^{\circ}$ (also, an angle in a triangle cannot be 200° as angles in a triangle are between 0° and 180°)

Step4: Check option C

$30^{\circ}+50^{\circ}+80^{\circ}=160^{\circ}
eq180^{\circ}$

Step5: Check option D

$40^{\circ}+50^{\circ}+90^{\circ}=180^{\circ}$

Answer:

D. 40°, 50°, 90°