Introduction to Trigonometry, Class 6

Here we have to teach sin, cos, etc..

Step 1
To begin with, simply tell students to draw a triangle ABC with AB =4 (Base), BC=3 (Altitude) and AC = 5 (Hypotenuse).

Step 2
Then tell them divide altitude by hypotenuse i.e 3 by 5 for nothing. It will be 0.6

Step 3
Then tell them to enlarge the same triangle and make hypotenuse 8 cm as well as the other sides. Now ask them to divide altitude by base. Continue this with hypotenuse 10, 12, 15 (select each bench for each one).

Step 4
Last conclude the result. It will remain same. Ask them why it remained same and let a while to discuss. They will answer that sides become large proportional.

Step 5
Now ask them, will the result be remain same if we do this for base and hypotenuse, altitude and base, and vise verse.

Step 6

Tell them it's difficult to repeat "altitude by hypotenuse" or "base by hypotenuse". So it's simple to name it such like Sine, Cose, Tangent, Cosec, Cosecant, Cotanget.