Easy Tricks To Find The Value of Theta (θ)

Trick 1: Finger Trick for Sin and Cos

This trick helps you quickly find Sin θ and Cos θ for 0°, 30°, 45°, 60°, and 90°.

Steps:

1. Spread your left hand and assign fingers to angles: Thumb → 0°, Index Finger → 30°, Middle Finger → 45°, Ring Finger → 60°, Little Finger → 90°.
2. To find sin θ: Count the number of fingers below the chosen finger and use the formula:

sin θ = √(Number of fingers below) / 2

3. To find cos θ: Count the number of fingers above the chosen finger and use the formula:

cos θ = √(Number of fingers above) / 2

Example: For sin 30°, 1 finger is below → sin 30° = √1/2 = 1/2.

Trick 2: Easy Memorization Table

Memorize Sin θ values with this trick:

Write:

sin θ = √0/2, √1/2, √2/2, √3/2, √4/2

For 0°, 30°, 45°, 60°, 90°.

🔹 This gives:

0, 1/2, √2/2, √3/2, 1

For Cos θ, just reverse the values of Sin θ!

🔹 This gives:

1, √3/2, √2/2, 1/2, 0