AIM: How can we find the area and circumference for a circle?
Announcements: The NYS Math Assessment for 7th Grade will be May 4-6. Please begin your preparations now.
HW: NYS Math Assessment Review Packet #35-51
Explain what a circle is. Provide a possible definition or detailed description.
We investigated the world of circles today. A circle is a round 2D figure whose points are the same distance from a center point. Circles also have diameters, which are segments that pass through the center and connect one side to the other. A radius is half the length of the diameter. It is a segment from the center to any point on the circle.
Since circles are special figures, they also have a special name for their perimeter, which is a circumference. This can be calculated by taking the diameter and multiplying it by pi (C=pi*d). It's important to remember that if you're given the circle's radius, you need to double it first to get the diameter.
Finding the area of a circle requires us to use the formula A=(pi)r^2. Remember to follow the order of operations and square the radius first before multiplying that amount by pi. Again, sometimes you'll be given the diameter, in which case you need to divide it in half to get the radius value which is substituted into the formula.