Question

On a coordinate plane, triangle D E F has points (negative 8, 8), (10, negative 2), and (negative 8, negative 8).

Answer 1

The area of the triangle DEF is approximately equal to 144.014 square units.

How to find the area of a triangle by Heron's formula

Triangles can be generated on a Cartesian plane by marking three non-colinear points on there. Heron's formula offers the possibility of calculating the area of a triangle by only using the lengths of its three sides, whose formula is now introduced:

A = √ [s · (s - DE) · (s - EF) · (s - DF)]     (1)

s = (DE + EF + DF) / 2     (2)

Where s is the semiperimeter of the triangle.

First, we determine the lengths of the sides DE, EF and DF by Pythagorean theorem:

Side DE

DE = √ [[10 - (- 8)]² + (- 2 - 8)²]

DE ≈ 20.591

Side EF

EF = √ [(- 8 - 10)² + [- 8 - (- 2)]²]

EF ≈ 18.974

Side DF

DF = √[[- 8 - (- 8)]² + (- 8 - 8)²]

DF = 16

Then, the area of the triangle DEF is by Heron's formula:

s = (16 + 18.974 + 20.591) / 2

s = 27.783

A = √[27.783 · (27.783 - 20.591) · (27.783 - 18.974) · (27.783 - 16)]

A ≈ 144.014

The area of the triangle DEF is approximately equal to 144.014 square units.

To learn more on Heron's formula: brainly.com/question/15188806

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Answer 2

Answer: 144

Step-by-step explanation:

The length of DF is 16.

The horizontal distance from DF to E is 18.

So, the area is $\frac{1}{2}(16)(18)=144$