I learned this shortcut memory trick from my Maths teacher in school. Recently while interacting with a class X student, I realized they have to mug up all the trigonometric ratios. This can be frustrating and can create a phobia or dislike for an interesting subject like Trigonometry at the very onset.

To use this memory trick, you need to memorize this simple mnemonic -

Some people have curly brown hair turned permanently black

That’s all you need to memorize to register the trigonometrical ratios in your mind forever. So here you go,

Some People Have

S = P/H

Sin = Perpendicular / Hypotenuse

Curly Brown Hair

C = B/H

Cos = Base/Hypotenuse

Turned Permanently Black

T = P/B

Tan = Perpendicular/Base

There are 3 more ratios: Cosec, Sec and Cot. For these, just remember that -

Cosec is the reciprocal of Sin; or Cosec = 1/Sin = H/P

Sec is the reciprocal of Cos; or Sec = 1/Cos = H/B

Cot is the reciprocal of Tan; or Cot= 1/Tan = B/P

In my next post I’ll write about a simple memory trick for memorizing the value of all major angles of different trigonometry ratios like sin30, cos45, tan60, etc.

Update on 4th September, 2011 – as promised above here’s the new post – http://www.quickermaths.com/memory-tricks-for-trigonometry/