# Surface Area of Solid Figures

## Mathematics, Grade 4

1
/
2
C = d or 2 r C = r 2 Area of a Circle Circumference of a Circle A E AB is a diameter AD, DB, and DC are radii EF is a cord B D C F center diameter circle D circumference radius chord A circle is a plane figure formed by a set of points that are equal distance from a fixed point within it, called the center. The diameter of a circle is the distance across the inside of a circle through the center. It is twice the measure of a radius. The radius is half the measure of a diameter. It is a line segment with one end point at the center of the circle and the other endpoint on the edge of the circle. The circumference of a circle is the distance around it. A chord is a line segment that connects any two points on a circle. The area of a circle is the space contained within the circumference. The ratio of the circumference of a circle to the diameter of a circle is approximately equal to 3.14 or . This ratio is called Pi ( ) and is the same for all circles. 22 7 d = 12 in. ; A = ? d = 12 A = r 2 A 3.14 (6) 2 A 3.14 36 A 113.04 in.2 C = 2 r C 2 3.14 5 C 31.4 ft r = 6 r = r = 5 ft ; C = ? d 2 r = 12 2 12 in. 5 ft C = d C 3.14 10 C 31.4 ft d = 10 ft ; C = ? © Copyright NewPath Learning. All Rights Reserved. 93-4610 www.newpathlearning.com Area & Circumference of Circles
\|xiBAHBDy01665mzV C = d or 2 r C = r 2 Area of a Circle Circumference of a Circle A E AB is a diameter AD, DB, and DC are radii EF is a cord B D C F circle D A circle is a formed by a set of points that are equal distance from a fixed point within it, called the . The of a circle is the distance across the inside of a circle through the . It is twice the measure of a . The is half the measure of a . It is a line segment with one end point at the center of the circle and the other endpoint on the edge of the circle. The of a circle is the distance around it. A is a line segment that connects any two points on a circle. The of a circle is the space contained within the circumference. The ratio of the circumference of a circle to the diameter of a circle is approximately equal to or . This ratio is called and is the same for all circles. d = 12 in. ; A = ? d = 12 A = r 2 A 3.14 ( 6 ) 2 A 3.14 36 A 113.04 in2 C = 2 r C 2 3.14 5 C 31.4 ft. r = 6 r = r = 5 ft ; C = ? r = 12 in. 5 ft C = d C 3.14 10 C 31.4 ft. d = 10 ft ; C = ? Key Vocabulary Terms area center chord circle circumference diameter pi ( ) plane figure radius © Copyright NewPath Learning. All Rights Reserved. 93-4610 www.newpathlearning.com Area & Circumference of Circles