Q. In the figure, O is the center of the circle. If the area of the shaded region is 42π, what is the diameter of the circle?
Circle Area Formula: We know the formula for the area of a circle is A=π⋅r2, where A is the area and r is the radius.
Setting up Equation: Given the area of the shaded region is 42π, we set up the equation 42π=π⋅r2.
Solving for Radius: We can cancel π from both sides of the equation, which leaves us with 42=r2.
Correcting Mistake: To find the radius, we take the square root of both sides, so r=42.
Correcting Mistake: To find the radius, we take the square root of both sides, so r=42.But wait, we made a mistake. We should have simplified 42 to 6×7 before taking the square root. Let's correct that.
More problems from Solve proportions: word problems