Math  /  Algebra

Question(1 point)
The area of a circular wave expands across a still pond such that its radius increases by 4 cm each second. Write a formula for the area AA of the circle as a function of time tt since the wave begins: A=A= \square

Studdy Solution

STEP 1

What is this asking? We need to find a formula that tells us the area of a circular wave at any given time, knowing that the wave's radius grows by 4 cm every second. Watch out! Don't forget that the problem asks for the area as a function of *time*, not radius.
We'll need to connect the radius to time somehow.

STEP 2

1. Relate radius and time
2. Express area in terms of time

STEP 3

Alright, so the radius increases by 44 cm every second.
This means that after tt seconds, the radius will have increased by 4t4 \cdot t cm.
Since the wave starts as a tiny point, we can say the **initial radius** is 00 cm.
Therefore, the radius rr at any time tt is given by r=4tr = 4 \cdot t cm.
Boom!

STEP 4

We know that the area AA of a circle with radius rr is given by the formula A=πr2A = \pi \cdot r^2.
This is our key to victory!

STEP 5

Now, let's **substitute** our expression for the radius in terms of time, r=4tr = 4 \cdot t, into the area formula.
This gives us A=π(4t)2A = \pi \cdot (4 \cdot t)^2.
We're so close, we can taste it!

STEP 6

Let's **simplify** this expression.
We have A=π(4t)2=π(16t2)=16πt2A = \pi \cdot (4 \cdot t)^2 = \pi \cdot (16 \cdot t^2) = 16 \cdot \pi \cdot t^2.
Fantastic!

STEP 7

The formula for the area AA of the circle as a function of time tt is A=16πt2A = 16 \cdot \pi \cdot t^2.

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