# Trigonometry

1 / 11
Slide 1: Slide
WiskundeMiddelbare schoolvwoLeerjaar 3

This lesson contains 11 slides, with text slides.

## Items in this lesson

SOH CAH TOA

Letters
Substitute
Calculate

#### Slide 3 -Slide

How to calculate the length of a side or angle in a right-angled triangle

- make a sketch
- include all known data (opposite, hypotenuse and adjacent sides)
- write down what you know and what you are trying to calculate so that you can use SOH CAH TOA to choose which ratio to use
- write down the ratio and fill in what you know

#### Slide 4 -Slide

when to use tan or shift tan?
Use  tan, sin and cos when you know the angle.

Use shift tan, shift sin and shift cos when you know the ratio of lengths of sides and you want to calculate the angle

#### Slide 6 -Slide

How to make a right-angled triangle by drawing an auxillary line
In a triangle that has no right-angle you first have to draw an auxillary line to make a right-angled triangle. You do this by drawing a line perpendicular to a side and passing through the opposite vertex.

#### Slide 8 -Slide

How to calculate an angle between two line segments in a solid
Look for a cross-section in which both line segments lie
Make a sketch of this cross-section and include all known date.
Check if you can calculate the angle. Sometimes you have to calculate the length of a line segment first.
Calculate the angle. Do not round the intermediate answers.

#### Slide 10 -Slide

Do you have any questions?