What is Soh Cah Toa?

By Ernesto Pérez

The Power of Mnemonics

and Why You Don't Need to

Hate Trigonometry

Was Soh Cah Toa a native American indian chief?

Was Soh Cah Toa an American indian teacher?

Or is Soh Cah Toa none of the above?

Yes, the correct answer is none of the above...because Soh Cah Toa is not a person.

In mathematics there are lots of terms and definitions that are hard to remember.

We can cope with them using mnemonic phrases.

Trigonometry is a field of math with many hard terms.

Mnemonic phrases are aids to remember something that otherwise is hard to retain in the mind.

In trigonometry, the right triangle is a very special one with unique properties not found in other triangles.Mnemonics is good here.

A

c

C

a

b

B

Let’ s see… in every right triangle ABC, the angle C is always a 90 degrees angle. This angle is called a right angle. Side c is the hypotenuse.

Every angle -written in uppercase- has two adjacent sides and one opposite side -written in lowercase.

The hypotenuse of a right triangle is the opposite side of the right angle.

A

c = hypotenuse

C

a

b

B

A

c

C

a

b

B

For any angle -say the angle A- there are three basic trigonometric functions:the sine of A, the cosine of A, and the tangent of A.

Now is the creepy moment of talking about the mnemonic Soh-Cah-Toa.

Are you ready?

The sine of A is the ratio of the opposite of A divided by the hypotenuse.

Sine =hypotenuse

opposite

See the Soh?

The Cosine of A is the ratio of the adjacent of A divided by the hypotenuse.

See the Cah?

Cosine = hypotenuse

adjacent

The Tangent of A is the ratio of the opposite of A divided by the adjacent.

See the Toa?

Tangent = adjacent

opposite

Sine = hypotenuse

opposite

Cosine = hypotenuse

adjacent

Tangent = adjacent

opposite

Nothing is simpler than that, you got it?

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