Question

finding the area of a triangle continued

estimate. circle all the problems that will have areas greater than 15 square inches. then find the exact areas of only the problems you circled.

13 explain two ways you can tell which triangles in problems 1 - 6 have an area greater than 15 square units.

Explanation:

Step1: Recall area formula

The area formula for a triangle is $A=\frac{1}{2}bh$, where $b$ is the base and $h$ is the height.

Step2: Calculate area of triangle 7

For triangle 7 with $b = 12$ in and $h=5$ in, $A_7=\frac{1}{2}\times12\times5 = 30$ in². Since $30>15$, we will calculate its exact - area.

Step3: Calculate area of triangle 8

For triangle 8 with $b = 4$ in and $h = 5$ in, $A_8=\frac{1}{2}\times4\times5=10$ in². Since $10<15$, we do not calculate its exact - area further.

Step4: Calculate area of triangle 9

For triangle 9 with $b = 14$ in and $h = 5$ in, $A_9=\frac{1}{2}\times14\times5=35$ in². Since $35>15$, we will calculate its exact - area.

Step5: Calculate area of triangle 10

For triangle 10 with $b = 7$ in and $h = 3$ in, $A_{10}=\frac{1}{2}\times7\times3 = 10.5$ in². Since $10.5<15$, we do not calculate its exact - area further.

Step6: Calculate area of triangle 11

For triangle 11 with $b = 20$ in and $h = 7$ in, $A_{11}=\frac{1}{2}\times20\times7=70$ in². Since $70>15$, we will calculate its exact - area.

Step7: Calculate area of triangle 12

For triangle 12 with $b=(12 + 8)$ in and $h = 4$ in, $A_{12}=\frac{1}{2}\times(12 + 8)\times4=\frac{1}{2}\times20\times4 = 40$ in². Since $40>15$, we will calculate its exact - area.

Answer:

Triangle 7: 30 square inches
Triangle 9: 35 square inches
Triangle 11: 70 square inches
Triangle 12: 40 square inches