Basic Geometry : Plane Geometry

Study concepts, example questions & explanations for Basic Geometry

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Example Questions

Example Question #1431 : Plane Geometry

Find the area.

6

Possible Answers:

\(\displaystyle 50\)

\(\displaystyle 100\)

\(\displaystyle 80\)

\(\displaystyle 75\)

Correct answer:

\(\displaystyle 50\)

Explanation:

Recall how to find the area of a triangle:

\(\displaystyle \text{Area}=\frac{\text{base}\times\text{height}}{2}\)

Since this is a right triangle, the base and the height are the two leg lengths given.

\(\displaystyle \text{Area}=\frac{20\times5}{2}=100\)

Example Question #1432 : Plane Geometry

Find the area.

7

Possible Answers:

\(\displaystyle 2.2875\)

\(\displaystyle 2.4875\)

\(\displaystyle 2.1875\)

\(\displaystyle 2.3875\)

Correct answer:

\(\displaystyle 2.1875\)

Explanation:

Recall how to find the area of a triangle:

\(\displaystyle \text{Area}=\frac{\text{base}\times\text{height}}{2}\)

Since this is a right triangle, the base and the height are the two leg lengths given.

\(\displaystyle \text{Area}=\frac{2.5\times1.75}{2}=2.1875\)

Example Question #1433 : Plane Geometry

Find the area of the triangle.

8

Possible Answers:

\(\displaystyle 5000\)

\(\displaystyle 3000\)

\(\displaystyle 4000\)

\(\displaystyle 6000\)

Correct answer:

\(\displaystyle 3000\)

Explanation:

Recall how to find the area of a triangle:

\(\displaystyle \text{Area}=\frac{\text{base}\times\text{height}}{2}\)

Since this is a right triangle, the base and the height are the two leg lengths given.

\(\displaystyle \text{Area}=\frac{100\times60}{2}=300\)

Example Question #1434 : Plane Geometry

Find the area.

9

Possible Answers:

\(\displaystyle 600\)

\(\displaystyle 800\)

\(\displaystyle 1200\)

\(\displaystyle 1000\)

Correct answer:

\(\displaystyle 600\)

Explanation:

Recall how to find the area of a triangle:

\(\displaystyle \text{Area}=\frac{\text{base}\times\text{height}}{2}\)

Since this is a right triangle, the base and the height are the two leg lengths given.

\(\displaystyle \text{Area}=\frac{40\times30}{2}=600\)

Example Question #1435 : Plane Geometry

Find the area.

10

Possible Answers:

\(\displaystyle 360\)

\(\displaystyle 180\)

\(\displaystyle 300\)

\(\displaystyle 240\)

Correct answer:

\(\displaystyle 240\)

Explanation:

Recall how to find the area of a triangle:

\(\displaystyle \text{Area}=\frac{\text{base}\times\text{height}}{2}\)

Since this is a right triangle, the base and the height are the two leg lengths given.

\(\displaystyle \text{Area}=\frac{40\times12}{2}=240\)

Example Question #1436 : Plane Geometry

Find the area.

11

Possible Answers:

\(\displaystyle 800\)

\(\displaystyle 100\)

\(\displaystyle 400\)

\(\displaystyle 600\)

Correct answer:

\(\displaystyle 400\)

Explanation:

Recall how to find the area of a triangle:

\(\displaystyle \text{Area}=\frac{\text{base}\times\text{height}}{2}\)

Since this is a right triangle, the base and the height are the two leg lengths given.

\(\displaystyle \text{Area}=\frac{40\times20}{2}=400\)

Example Question #260 : Right Triangles

Find the area.

12

Possible Answers:

\(\displaystyle 144\)

\(\displaystyle 72\sqrt3\)

\(\displaystyle 36\)

\(\displaystyle 36\sqrt3\)

Correct answer:

\(\displaystyle 72\sqrt3\)

Explanation:

Recall how to find the area of a triangle:

\(\displaystyle \text{Area}=\frac{\text{base}\times\text{height}}{2}\)

However, the question gives us the length of a height and the length of the hypotenuse. Thus, we will need to use the Pythagorean Theorem to find the length of the base.

\(\displaystyle \text{Hypotenuse}^2=\text{base}^2+\text{height}^2\)

Now, rewrite the equation to solve for the height.

\(\displaystyle \text{height}^2=\text{Hypotenuse}^2-\text{base}^2\)

\(\displaystyle \text{height}=\sqrt{\text{Hypotenuse}^2-\text{base}^2}\)

Plug in the values of the hypotenuse and base to find the height.

\(\displaystyle \text{height}=\sqrt{24^2-12^2}=\sqrt{432}=12\sqrt3\)

Now, plug the values of the base and the height to find the area.

\(\displaystyle \text{Area}=\frac{12\sqrt3\times12}{2}=72\sqrt3\)

Example Question #1437 : Plane Geometry

Find the area.

5

Possible Answers:

\(\displaystyle 0.3125\)

\(\displaystyle 1.350\)

\(\displaystyle 1.225\)

\(\displaystyle 0.875\)

Correct answer:

\(\displaystyle 0.3125\)

Explanation:

Recall how to find the area of a triangle:

\(\displaystyle \text{Area}=\frac{\text{base}\times\text{height}}{2}\)

Since this is a right triangle, the base and the height are the two leg lengths given.

\(\displaystyle \text{Area}=\frac{2.5\times0.25}{2}=0.3125\)

Example Question #1432 : Plane Geometry

Find the area.

1

Possible Answers:

\(\displaystyle \frac{169}{}\)

\(\displaystyle \frac{169\sqrt3}{2}\)

\(\displaystyle \frac{13\sqrt3}{2}\)

\(\displaystyle 169\)

Correct answer:

\(\displaystyle \frac{169\sqrt3}{2}\)

Explanation:

Recall how to find the area of a triangle:

\(\displaystyle \text{Area}=\frac{\text{base}\times\text{height}}{2}\)

Now, we have the height and the hypotenuse from the question. Use the Pythagorean Theorem to find the length of the base.

\(\displaystyle \text{hypotenuse}^2=\text{base}^2+\text{height}^2\)

\(\displaystyle \text{base}^2=\text{hypotenuse}^2-\text{height}^2\)

\(\displaystyle \text{base}=\sqrt{\text{hypotenuse}^2-\text{height}^2}\)

Substitute in the values of the height and hypotenuse.

\(\displaystyle \text{base}=\sqrt{26^2-13^2}=\sqrt{507}=13\sqrt3\)

Simplify.

\(\displaystyle \text{base}=\sqrt{507}\)

Reduce.

\(\displaystyle \text{base}=13\sqrt3\)

Now, substitute in the values of the base and the height to find the area.

\(\displaystyle \text{Area}=\frac{13 \times 13\sqrt3}{2}\)

Solve.

\(\displaystyle \text{Area}=\frac{169\sqrt3}{2}\)

Example Question #57 : How To Find The Area Of A Right Triangle

Find the area.

2

Possible Answers:

\(\displaystyle 48\)

\(\displaystyle 4\sqrt3\)

\(\displaystyle 16\)

\(\displaystyle 2\sqrt3\)

Correct answer:

\(\displaystyle 2\sqrt3\)

Explanation:

Recall how to find the area of a triangle:

\(\displaystyle \text{Area}=\frac{\text{base}\times\text{height}}{2}\)

Now, we have the height and the hypotenuse from the question. Use the Pythagorean Theorem to find the length of the base.

\(\displaystyle \text{hypotenuse}^2=\text{base}^2+\text{height}^2\)

\(\displaystyle \text{base}^2=\text{hypotenuse}^2-\text{height}^2\)

\(\displaystyle \text{base}=\sqrt{\text{hypotenuse}^2-\text{height}^2}\)

Substitute in the values of the height and hypotenuse.

\(\displaystyle \text{base}=\sqrt{4^2-2^2}\)

Simplify.

\(\displaystyle \text{base}=\sqrt{12}\)

Reduce.

\(\displaystyle \text{base}=2\sqrt3\)

Now, substitute in the values of the base and the height to find the area.

\(\displaystyle \text{Area}=\frac{2 \times 2\sqrt3}{2}\)

Solve.

\(\displaystyle \text{Area}=2\sqrt3\)

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