MHT CET 2021 Math Solved Paper

Let a be the side of an equilateral triangle and A be the area of an equilateral triangle. Then, ‌

da

dt

=2cm∕s
We know that, area of an equilateral triangle
A=‌

√3

4

a2
On differentiating both sides w.r.t. t, we get
‌

dA

dt

‌‌=‌

√3

4

×2a×‌

da

dt

⇒‌‌‌

dA

dt&

=‌

√3

4

×2×20×2‌‌‌ [given ‌a=20]
∴‌‌

dA

dt

‌‌=20√3cm2∕s
Thus, the rate of area increasing is 20√3cm2∕s.