G S Rehill's Interactive Maths Software Series - "Building a Strong Foundation in Mathematics" from mathsteacher.com.au.

Order a 12-month Year 7 Interactive Maths software Homework Licence for only $19.95. Order a 12-month Year 8 Interactive Maths software Homework Licence for only $19.95. Order a 12-month Year 9 Interactive Maths software Homework Licence for only $19.95. Order a 12-month Year 10 Interactive Maths software Homework Licence for only $19.95.

Year 9 Interactive Maths - Second Edition


Naming the Sides of a Right-Angled Triangle

The side opposite the right angle is called the hypotenuse.  It is the largest side of a right-angled triangle.

If you stand at A in the triangle ABC, the side BC is opposite to you and the side AB is next to you.  We therefore say that BC is the opposite side to angle A and AB is the adjacent side to angle A.


Notation


Trigonometric Ratios



If you have trouble remembering the definitions, just remember SOH CAH TOA.


Using a Graphics Calculator

If you have a TI-83 graphing calculator, select Degree from the MODE menu and set Float to 4 to obtain the answers correct to 4 decimal places.  Press QUIT to return to the Home Screen and clear the screen if necessary.

If you are using another calculator, consult its instruction booklet or ask your teacher how you can set its Mode to 'Degree mode' and the decimal places display to 4 places.


Example 1

Evaluate the following to 4 decimal places:

Solution:

         


Recall that:

 


This is abbreviated as follows:


Example 2

Solution:


Key Terms

hypotenuse, adjacent side, opposite side, theta, trigonometric ratios, sine, sin, cosine, cos, tangent, tan, SOH, CAH, TOA, SOH CAH TOA, degrees, minutes, seconds


| Home Page | Order Maths Software | About the Series | Maths Software Tutorials |
| Year 7 Maths Software | Year 8 Maths Software | Year 9 Maths Software | Year 10 Maths Software |
| Homework Software | Tutor Software | Maths Software Platform | Trial Maths Software |
| Feedback | About mathsteacher.com.au | Terms and Conditions | Our Policies | Links | Contact |

Copyright © 2000-2022 mathsteacher.com Pty Ltd.  All rights reserved.
Australian Business Number 53 056 217 611

Copyright instructions for educational institutions

Please read the Terms and Conditions of Use of this Website and our Privacy and Other Policies.
If you experience difficulties when using this Website, tell us through the feedback form or by phoning the contact telephone number.