Explanation

Given sinθ = 3/5, 1st quadrant

Use identity: sin²θ + cos²θ = 1

(3/5)² + cos²θ = 1  

9/25 + cos²θ = 1  

cos²θ = 1 - 9/25 = 16/25  

cosθ = ±4/5

In 1st quadrant both sin and cos are positive.  

So cosθ = 4/5.

Last verified on 04-05-2026

Explanation

• π (pi) is an irrational number (cannot be written as a fraction).
• When we divide π by 3, it is still irrational.
• Irrational numbers are decimals that never end and never repeat.

Last verified on 08-06-2026

Explanation

tan 45° = 1

cot 45° = 1

tan² 45° + cot² 45°

= 1² + 1²

= 1 + 1

= 2

Last verified on 19-03-2026

Explanation

The sum of the first 10 natural numbers is:

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 = 55

Average = 55/10 = 5.5

OR

Formula for natural number= n(n+1)/2

n=10

Now

10(10+1)/2

10(11)/2

5(11)

55

Last verified on 15-02-2026

Explanation

Surface area = 4πr², Volume = 4/3πr³.  

Surface area is just derivative of volume w.r.t r.

2πr is circumference of a circle, not volume at all.

Last verified on 07-06-2026