Year 9

Year 9

# Finding missing sides using sine and cosine for any angle

## Lesson details

### Key learning points

1. In this lesson, we will learn how to find missing sides using sine and cosine for any angle in a triangle.

### Licence

This content is made available by Oak National Academy Limited and its partners and licensed under Oak’s terms & conditions (Collection 1), except where otherwise stated.

## Video

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## Worksheet

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## Starter quiz

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### 7 Questions

Q1.
Complete the statement: In a right angled triangle that has an interior angle of 30 degrees, opposite/ hypotenuse = .................
0.2
0.87
Q2.
Complete the statement: In a right angled triangle that has an interior angle of 60 degrees, opposite/ hypotenuse = .................
0.2
0.5
Q3.
Complete the statement: In a right angled triangle that has an interior angle of 60 degrees, adjacent/ hypotenuse = .................
0.2
0.87
Q4.
Complete the statement: In a right angled triangle that has an interior angle of 30 degrees, adjacent/ hypotenuse = .................
0.2
0.5
Q5.
What is the length of side a?
3.4 cm
6 cm
Q6.
What is the length of side b?
10 cm
3.5 cm
Q7.
What is the size of angle a?
45 degrees
60 degrees

## Exit quiz

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### 7 Questions

Q1.
What is the length of side marked q ?
10 cm
5 cm
Q2.
What is the length of the side marked r ?
15 cm
22 cm
Q3.
What is the correct step for calculating the length of side b?
Option 2
Option 3
Q4.
What is the length of of b correct to 1 decimal place?
0.86 cm
10 cm
Q5.
What is the correct step for calculating the length of side a?
Option 1
Option 2