We can find the area using trigonometry. Given that the radii of the circles are the same, we can deduce that the shaded area in the circles are the same, so to solve the problem, we will find the shaded area in one of the circles and double our answer.
First, we know that the radius can be drawn from the center to any point on the edge of the circle. Therefore we can create an isosceles triangle by drawing the radius from the center to the other end of the chord of length 4 (see attached photo for triangle).
Next, we can find the angle formed at the center of the circle using a trigonometry function. We know that the chord opposite of the angle is 4 long and that both adjacent sides are 4 long. If we draw the amplitude of the triangle which bisects the center angle, we will have two right triangles. The side opposite to the new center angle is 2 long. Now we can use the sine function to find the angle:
If half of the center angle is 30 degrees, then we know that the angle between the radii is 60 degrees. Since a full circle is 360 degrees, we know that we are dealing with one-sixth of the circle.
Now we need to find the area of one-sixth of the circle and subtract the area of the triangle to find the shaded area.
To find the area of the triangle, we can use one-half base times height, but first we need to find the height. We can use the tangent function to find it:
So the area of the shaded section is:
So multiply that by two to get the area for both circles and the final answer is:
A = 2.8988
First, we know that the radius can be drawn from the center to any point on the edge of the circle. Therefore we can create an isosceles triangle by drawing the radius from the center to the other end of the chord of length 4 (see attached photo for triangle).
Next, we can find the angle formed at the center of the circle using a trigonometry function. We know that the chord opposite of the angle is 4 long and that both adjacent sides are 4 long. If we draw the amplitude of the triangle which bisects the center angle, we will have two right triangles. The side opposite to the new center angle is 2 long. Now we can use the sine function to find the angle:
If half of the center angle is 30 degrees, then we know that the angle between the radii is 60 degrees. Since a full circle is 360 degrees, we know that we are dealing with one-sixth of the circle.
Now we need to find the area of one-sixth of the circle and subtract the area of the triangle to find the shaded area.
To find the area of the triangle, we can use one-half base times height, but first we need to find the height. We can use the tangent function to find it:
So the area of the shaded section is:
So multiply that by two to get the area for both circles and the final answer is:
A = 2.8988