# Use trigonometry to find the perpendicular height of a triangle

In this lesson, we will identify the perpendicular height of triangles, use trigonometry to find the perpendicular height and apply this to find the area of a triangle.

#### Unit quizzes are being retired in August 2023

Why we're removing unit quizzes from the website >
Quiz:

# Intro quiz - Recap from previous lesson

Before we start this lesson, let’s see what you can remember from this topic. Here’s a quick quiz!

Q1.A ladder leans against a wall. It is 3m away from the wall at an angle of 60 degrees. What is the length of the ladder?

1/3

Q2.A man stands exactly 8m from a lamppost. He looks to the top of the lamppost, as shown. What is the height of the lamppost? Answer to 1 dp

2/3

Q3.Find the perpendicular height of this parallelogram ( to 1 dp)

3/3

#### Unit quizzes are being retired in August 2023

Why we're removing unit quizzes from the website >
Quiz:

# Intro quiz - Recap from previous lesson

Before we start this lesson, let’s see what you can remember from this topic. Here’s a quick quiz!

Q1.A ladder leans against a wall. It is 3m away from the wall at an angle of 60 degrees. What is the length of the ladder?

1/3

Q2.A man stands exactly 8m from a lamppost. He looks to the top of the lamppost, as shown. What is the height of the lamppost? Answer to 1 dp

2/3

Q3.Find the perpendicular height of this parallelogram ( to 1 dp)

3/3

# Video

Click on the play button to start the video. If your teacher asks you to pause the video and look at the worksheet you should:

• Click "Close Video"
• Click "Next" to view the activity

Your video will re-appear on the next page, and will stay paused in the right place.

# Worksheet

These slides will take you through some tasks for the lesson. If you need to re-play the video, click the ‘Resume Video’ icon. If you are asked to add answers to the slides, first download or print out the worksheet. Once you have finished all the tasks, click ‘Next’ below.

#### Unit quizzes are being retired in August 2023

Why we're removing unit quizzes from the website >
Quiz:

# Use trigonometry to find the perpendicular height of a triangle

Don’t worry if you get a question wrong! Forgetting is an important step in learning. We will recap next lesson.

Q1.If b is the base, identify the perpendicular height of this triangle.

1/3

Q2.Find the perpendicular height of the triangle.

2/3

Q3.Find the perpendicular height of the triangle. Give your answer to one decimal place.

3/3

#### Unit quizzes are being retired in August 2023

Why we're removing unit quizzes from the website >
Quiz:

# Use trigonometry to find the perpendicular height of a triangle

Don’t worry if you get a question wrong! Forgetting is an important step in learning. We will recap next lesson.

Q1.If b is the base, identify the perpendicular height of this triangle.

1/3

Q2.Find the perpendicular height of the triangle.

2/3

Q3.Find the perpendicular height of the triangle. Give your answer to one decimal place.

3/3

# Lesson summary: Use trigonometry to find the perpendicular height of a triangle

## Time to move!

Did you know that exercise helps your concentration and ability to learn?

For 5 mins...

Move around:
Walk

On the spot:
Dance