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Easy tip to memorize trigonometric formulae in SPM and beyond

Published by Afterschool.my on Jan 18, 2021, 03:03 pm

Who says there is no art in Mathematics?

confusing doodle math formula stress

Ever been stumped during Math exams because you just can't remember how to get a tan (x) when given sin (x) and cos (x)? trust me, you'll need to know this until the very end of your uni years!

In trigonometry, it is common to use mnemonics (the study and development of systems for improving and assisting the memory) to help remember trigonometric identities and the relationships between the various trigonometric functions.

For example, the sine, cosine, and tangent ratios in a right triangle can be remembered by representing them as strings of letters, for instance SOH-CAH-TOA in English:

Sine = Opposite ÷ Hypotenuse

Cosine = Adjacent ÷ Hypotenuse

Tangent = Opposite ÷ Adjacent

One way to remember the letters is to say the short forms out loud. Another method is to expand the letters into a sentence, such as "Some Old Houses Can Always Hide Their Old Age".

If you speak Chinese (especially the Hokkien dialect), you can also remember it as TOA-CAH-SOH, which also means 'big-footed woman'.

Let us tell you about another way to remember which combination of trigonometry function goes with which one to produce another one. Confused?

Introducing, the:

Hexagon of Trigonometric Identities! trigonometry

This powerful mnemonic is easily reproducible by memory, with functions on one side and co-functions on the other, a 1 in the middle, and three triangles pointed down.

Here's a list on how best to read this diagram: screenshot-en.wikipedia.org 2016-08-08 14-52-21

If you’re looking for any last-minute additions to your library of workbooks, why not download Afterschool’s SPM 2021 February Spot Questions right here for absolutely FREE! Covering subjects from Bahasa Malaysia and Additional Mathematics to Physics and Chemistry, these questions have been meticulously curated by dedicated teachers based on papers from previous years. The SPM 2021 February Spot Questions consists of spot questions based on a 10-year analysis of past year papers identified by teachers with 20+ years of experience. 

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