All the solutions provided in **McGraw Hill My Math Grade 4 Answer Key PDF Chapter 14 Lesson 8 Triangles **will give you a clear idea of the concepts.

## McGraw-Hill My Math Grade 4 Answer Key Chapter 14 Lesson 8 Triangles

There are many different kinds of triangles. You can classify triangles by the measure of their angles.

**Math in My World**

**Example 1**

This sandwich is cut in half. Classify the triangle represented by the half sandwich as right, acute, or obtuse. Determine if any of the sides are perpendicular.

A right triangle has one right angle.

How many right angles are there? _____________

The two sides that form the right angle are perpendicular.

An acute triangle has three acute angles.

How many acute angles are there? _____________

An obtuse triangle has one obtuse angle.

How many obtuse angles are there? _____________

So, the triangle is a(n) _____________ triangle.

Answer: How many right angles are there? One

How many acute angles are there? Three

How many obtuse angles are there? One

So, the triangle is a(n) right triangle.

**Example 2**

Classify the triangle as right, acute, or obtuse. Identify the vertices and line segments of the triangle.

The triangle ¡s a(n) _____________ triangle because it has one _____________ angle.

There are _____________ vertices. List them below.

Vertices: _____________

There are _____________ line segments. List them below.

Line Segments: _____________

Answer: The triangle is a(n) obtuse triangle because it has one obtuse angle. An obtuse angle is an angle which is greater than 90 degrees and less than 180 degrees.

There are 3 vertices. List them below.

Vertices: L, M and P

There are 3 line segments. List them below.

Line Segments: LM, MP, LP

**Talk Math**

Is it possible for a triangle to have a pair of parallel sides? Explain.

Answer: Not possible

No, it is not possible for a triangle to have a pair of parallel lines.

A triangle cannot have parallel lines because it must have three angles that are 180 degrees to prevent the three sides from intersecting. Parallel lines can never intersect, and triangles must always have intersecting sides.

**Guided Practice**

Question 1.

Classify the triangle as acute, right, or obtuse. Determine how many sides are perpendicular

The triangle is _____________.

_______________ sides are perpendicular.

Answer: The triangle is obtuse triangle.

An obtuse angle is an angle which is greater than 90 degrees and less than 180 degrees.

No (0) sides are perpendicular.

The obtuse angle triangle cannot have perpendicular sides. Only the pair of sides that form a right angle in right triangle are perpendicular to each other.

### McGraw Hill My Math Grade 4 Chapter 14 Lesson 8 My Homework Answer Key

**Practice**

**Identify the perpendicular sides of each right triangle.**

Question 1.

Answer: VZ and ZX

Only the pair of sides that form a right angle in right triangle are perpendicular to each other. In the above figure, we can observe that VZ and ZX sides are perpendicular to each other.

Question 2.

Answer: KM and QM

Only the pair of sides that form a right angle in right triangle are perpendicular to each other. In the above figure, we can observe that KM and QM sides are perpendicular to each other.

**Classify each triangle as acute, right, or obtuse. Determine how many sides appear to be perpendicular.**

Question 3.

Answer: Right triangle

As you can observe the above figure, there is a 90 degrees angle, so the triangle is called as right angled triangle.

Only the pair of sides that form a right angle in right triangle are perpendicular to each other. Therefore, two sides are appear to be in perpendicular to each other.

Question 4.

Answer: Obtuse triangle

As you can observe the above figure, there is one obtuse angle, so the triangle is called as obtuse angled triangle.

The obtuse angle triangle cannot have perpendicular sides. Only the pair of sides that form a right angle in right triangle are perpendicular to each other.

**Problem Solving**

Question 5.

**Mathematical PRACTICE** Justify Conclusions Can a triangle have two right angles? Explain.

Answer: A triangle cannot have two right angles.

If a triangle has two right angles, then the sum of its three angles will be more than the two right angles i.e. more than 180∘ which is impossible.

**Vocabulary Check**

Draw a line to match each vocabulary term to its example.

Answer:

6. Acute triangle: An acute triangle has three acute angles.

7. Obtuse triangle: An obtuse triangle has one obtuse angle.

8. Right triangle: A right triangle has one right angle.

**Test Practice**

Question 9.

Which is an acute triangle?

Answer: A

An acute triangle has three acute angles.