Lesson 8.3 Practice

Answer explanation

All three angles in a triangle add up to 180 degrees. So 180 - 105 - 42 = 33.

Can the following side lengths form a triangle?

14 m, 19 m, 9 m

• Yes

• No

Answer explanation

14 + 9 = 23

23 > 19

So YES! They are a triangle.

Can the following side lengths form a triangle?

8 cm, 10 cm, 12 cm

• Yes

• No

Answer explanation

10 + 8 = 18

18 > 12

So YES! They are a triangle.

Can the following side lengths form a triangle?

7 in, 2 in, 4in

• Yes

• No

Answer explanation

2 + 4 = 6

6 > 7

6 is not greater than 7. So NO! They are not a triangle.

A triangle has two sides that are 4 inches and 9 inches long. Which value(s) could be the length of the third side?

• 13 inches

• 3 inches

• 14 inches

• 6 inches

• 5 inches

Answer explanation

4 + 9 = 13 and 9 - 4 = 5

So the third side length must be between 5 inches and 13 inches.

Find the missing angle measure in the triangle.

Answer explanation

All three angles in a triangle add up to 180 degrees. So 180 - 90 - 34 = 56.

Find the missing angle measure in the triangle.

Answer explanation

All three angles in a triangle add up to 180 degrees. So 180 - 72 - 38 = 70.

If you have two triangles that both have side lengths of 3 in, 4 in, and 5 in, are they the same size, same shape, or both?

• Same Size

• Same Shape

• Both

Answer explanation

Side-Side-Side Rule says that two triangles with the exact same side length are the same size AND same shape.

• Same Size

• Same Shape

• Both

Answer explanation

Angle-Angle-Angle Rule says that two triangles with the exact same angle measures are the same shape but not necessarily the same size.

Two sides of a triangle are 10 meters and 7 meters. What two values must the third side be between?

Answer explanation

10 + 7 = 17 and 10 - 7 = 3

So the third side length must be between 3 meters and 17 meters.