Big Ideas Math Geometry, 2014
BI
Big Ideas Math Geometry, 2014 View details
4. Perimeter and Area in the Coordinate Plane
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Exercise 14 Page 34

Draw the polygon. What do you need to know to be able to calculate its area?

24.5 square units

Practice makes perfect

When drawing the polygon, the first thing we should notice is its shape. This polygon has three vertices, so it's a triangle. Let's draw it in a coordinate plane.

To calculate the triangle's area, we can use the formula for the area of a triangle.

A=1/2bh In this formula, b is the length of the base of the triangle and h is the height of the triangle. The base of this triangle is the side JK. The height spans from JK to point L. Let's mark the height.

We can find the length of the base using the Ruler Postulate with the x-coordinates. JK=|4 - (- 3)|=7 Thus, b= 7. The height can be found by counting the unit grid lines. From the base to L, there are seven units. Therefore, h= 7. Now we are ready to calculate the area of the triangle.
A=1/2bh
A=1/2( 7)( 7)
A=24.5
The triangle's area is 24.5 square units.