Grade 6 · Math

6th grade Angles and sides of triangles worksheet

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Angles and sides of triangles

Grade 6 Math Worksheet - Challenge Me

NameDate

Circle the best answer, or write your answer on the line.

Luz sketches a boat sail as an isosceles triangle. Its top angle is 40°, and its two base angles are equal. How big is each base angle, in degrees?
Milo sketches a tower roof end as an isosceles triangle. Its top angle is 100°, and its two base angles are equal. How big is each base angle, in degrees?
Noah sketches a castle pennant as an isosceles triangle. Its top angle is 20°, and its two base angles are equal. How big is each base angle, in degrees?
Pia sketches a tent end as an isosceles triangle. Its top angle is 80°, and its two base angles are equal. How big is each base angle, in degrees?
Ari sketches a castle roof end as an isosceles triangle. Its two equal base angles are 25° each. How big is the top angle, in degrees?
Kira fences a triangular duck pond. Two fences are 4 ft and 9 ft long. The third fence is a whole number of feet. What is the shortest the third fence can be?
Milo fences a triangular carrot patch. Two fences are 6 ft and 14 ft long. The third fence is a whole number of feet. What is the shortest the third fence can be?
8.
Bo draws triangle ABC on a map. Corner A is 45° and corner B is 70°. Which side is the longest?
- Side BC
- Side CA
- Side AB
9.
Esme draws triangle ABC on a map. Corner A is 30° and corner B is 50°. Which side is the longest?
- Side CA
- Side BC
- Side AB
10.
Jun draws triangle ABC on a map. Corner A is 35° and corner B is 55°. Which side is the longest?
- Side AB
- Side CA
- Side BC

6th grade Angles and sides of triangles worksheet – printable — Print: 1 2 3 4 5 6

About this worksheet

Angles and sides of triangles. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

I can find the third angle of a triangle because all three angles make 180 degrees.
I can tell whether three lengths can make a triangle by adding the two shorter ones.
I can find how long or how short the third side can be when two sides are known.
I can find the longest side from the angles, and the largest angle from the sides, because they sit across from each other.

Standard: state-only (CCSS 4.G.A.1, 4.MD.C.5–7, 7.G.A.2 three lengths make a triangle, 8.G.A.5 angle sum)

Words to know

angle: The space between two lines that meet at a corner, measured in degrees.

degree: A unit for angles. A straight line is 180 degrees.

right angle: A square corner, 90 degrees.

isosceles triangle: A triangle with two equal sides. The angles opposite them are equal too.

base angles: The two equal angles of an isosceles triangle, next to the unequal side.

side: One of the straight edges of a triangle.

across from: The side that does not touch a corner, or the corner that does not touch a side.

flat: Sides that lie in one line with no corner, so there is no triangle.

Common mistakes

Your child used 360° as the total of a triangle's angles. 360° is a full turn. Cut the three corners off a paper triangle and fit them side by side along a ruler: they make a straight line, which is 180°.

Your child added the two angles they were given. The missing angle is what is left over when you take those two away from 180°.

Your child left the right angle out when finding the missing angle. A right triangle already uses 90° of its 180° on the square corner.

What to say

Ask: will the missing angle be bigger or smaller than the two angles put together?

Ask: which angles have you taken away from 180°?

Questions parents ask

What is the most common mistake with angles and sides of triangles?

Are these 6th grade math worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

More grade 6 math

See all grade 6 math

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