2/5 = 42
1/5 = 21
5/5 = 105
105 students in the class
Answer:
:)
Step-by-step explanation:
For simplicity I will substitue
for β.

In the first step I used the identity
And I factored out 
Then it's just simple algebra to cancel till the 3rd step where we used another identity derived from the Pythagorean Theorem.

That's it!
40 cm.
let the length of the first part be 3x, second part be 4x, third part be 5x.
where x is a positive length in cm.
why 3x,4x and 5x ?
so that the ratio of lengths of the 3 parts be 3:4:5.
total length of the stick = 3x + 4x + 5x = 12x=96cm
so x=96/12 = 8cm
therefore the largest part of the stick (5x)= 5*8 =40cm