## How to remember the exact values of trigonometric functions

When you see the table shown below of exact values of the trigonometric functions sin(*x*), cos(*x*) and tan(*x*) you always wonder "How am I going to remember them!?".

Here is an easy way to work them out without having to memorise them.

First of all the sine function increases from 0° to 90°.

sin(0°) = **0** and sin(90°) = **1**

**Step 1 **Write the numbers **1**, **2** and **3** from left to right in the empty cells in the sin(*x*) row as shown below.

**Step 2**** **Square root these three numbers.

**Step 3**** **Draw a fraction line underneath each number.

**Step 4**** **Write a **2** at the denominator of each fraction.

... and this is how you can remember the exact values for the sine function from 0° to 90°.

The exact values for the cosine function from 0° to 90° can be worked out in a similar manner.

First of all the cosine function decreases from 0° to 90°.

cos(0°) = **1** and cos(90°) = **0**

**Step 1 **Write the numbers **3**, **2** and **1** from left to right in the empty cells in the cos(*x*) row as shown below.

**Step 2**** **Square root these three numbers.

**Step 3**** **Draw a fraction line underneath each number.

**Step 4**** **Write a **2** at the denominator of each fraction.

... and this is how you can remember the exact values for the cosine function from 0° to 90°.