Grades 9-10 Video Solutions 2023-2023_9-10

Video Transcription

The large rectangle in the diagram is divided into 30 equal squares as shown. The perimeter of the shaded region is 240 cm. What is the area of the rectangle?  We can count how many sides we have of our shaded region and starting from let's say the top right, if we go around the figure making sure that we're careful not to double  count any sides, we'll find that the shaded region has exactly 30 sides. Because the perimeter of our shaded region is 240 cm, that means that we must have a side length of 8 cm.  So each square, each small square has a side length of 8 cm and we're told that the large rectangle in the diagram is divided into 30 equal squares.  To find the area of our large rectangle, we can find 30 x 8 x 8, which we know is 1920 cm2.

Video Summary

The large rectangle in the diagram is divided into 30 equal squares as shown. The perimeter of the shaded region is 240 cm. What is the area of the rectangle? We can count how many sides we have of our shaded region and starting from let's say the top right, if we go around the figure making sure that we're careful not to double count any sides, we'll find that the shaded region has exactly 30 sides. Because the perimeter of our shaded region is 240 cm, that means that we must have a side length of 8 cm. So each square, each small square has a side length of 8 cm and we're told that the large rectangle in the diagram is divided into 30 equal squares. To find the area of our large rectangle, we can find 30 x 8 x 8, which we know is 1920 cm2.

Keywords

rectangle

shaded region

perimeter

area

squares