Find Circle Area: Perpendicular Radii with Distance y+2

Question

Given a circle whose center O. From the center of the circle go out 2 radii that cut the circle at the points A and B.

Given AO⊥OB.

The side AB is equal to and+2.

Express band and the area of the circle.

y+2y+2y+2AAABBBOOO

Video Solution

Solution Steps

00:00 Express the area of the circle using Y
00:03 Circle radius
00:10 Let's use the Pythagorean theorem in triangle AOB
00:19 Let's properly open the parentheses
00:35 Let's isolate R squared
00:46 Let's use the formula for calculating circle area
00:49 Let's substitute the R we just found
01:03 And this is the solution to the question

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Identify the given information.
  • Use the geometric properties of a circle and a right triangle to find the radius.
  • Express the area of the circle in terms of the given expression.

Now, let's work through each step:

Step 1: Given a circle with center O O and radii AO AO and OB OB such that AOOB AO\perp OB , each is a radius r r , and AB=and+2 AB = \text{and}+2 .

Step 2: By the Pythagorean theorem, we know:

AO2+OB2=AB2 AO^2 + OB^2 = AB^2 r2+r2=(y+2)2 r^2 + r^2 = (y+2)^2 2r2=y2+4y+4 2r^2 = y^2 + 4y + 4

Step 3: Solving for the area of the circle:

The radius r r can be expressed by rearranging:

r2=y2+4y+42 r^2 = \frac{y^2 + 4y + 4}{2}

The area of the circle using this radius is:

Area=πr2=π(y2+4y+42)=π2(y2+4y+4) \text{Area} = \pi r^2 = \pi \left(\frac{y^2 + 4y + 4}{2}\right) = \frac{\pi}{2}(y^2 + 4y + 4)

Therefore, the expression for the area of the circle is π2[y2+4y+4] \frac{\pi}{2}[y^2+4y+4] .

Answer

π2[y2+4y+4] \frac{\pi}{2}[y^2+4y+4]