Basic Geometry : Plane Geometry

Study concepts, example questions & explanations for Basic Geometry

varsity tutors app store varsity tutors android store

Example Questions

Example Question #591 : Plane Geometry

If the perimeter of a rectangle is \(\displaystyle 36\), and the width of the rectangle is \(\displaystyle 11\), what is the area of the rectangle?

Possible Answers:

\(\displaystyle 91\)

\(\displaystyle 84\)

\(\displaystyle 98\)

\(\displaystyle 77\)

Correct answer:

\(\displaystyle 77\)

Explanation:

Recall how to find the perimeter of a rectangle:

\(\displaystyle \text{Perimeter}=2(\text{length}+\text{width})\)

Since we are given the width and the perimeter, we can solve for the length.

\(\displaystyle \text{length}+\text{width}=\frac{\text{Perimeter}}{2}\)

\(\displaystyle \text{length}=\frac{\text{Perimeter}}{2}-\text{width}\)

Substitute in the given values for the width and perimeter to find the length.

\(\displaystyle \text{length}=\frac{36}{2}-11\)

Simplify.

\(\displaystyle \text{length}=18-11\)

Solve.

\(\displaystyle \text{length}=7\)

Now, recall how to find the area of a rectangle.

\(\displaystyle \text{Area}=\text{length}\times\text{width}\)

Substitute in the values of the length and width to find the area.

\(\displaystyle \text{Area}=11 \times 7\)

Solve.

\(\displaystyle \text{Area}=77\)

Example Question #31 : How To Find The Area Of A Rectangle

If the perimeter of a rectangle is \(\displaystyle 36\), and the width of the rectangle is \(\displaystyle 10\), what is the area of the rectangle?

Possible Answers:

\(\displaystyle 70\)

\(\displaystyle 80\)

\(\displaystyle 90\)

\(\displaystyle 100\)

Correct answer:

\(\displaystyle 80\)

Explanation:

Recall how to find the perimeter of a rectangle:

\(\displaystyle \text{Perimeter}=2(\text{length}+\text{width})\)

Since we are given the width and the perimeter, we can solve for the length.

\(\displaystyle \text{length}+\text{width}=\frac{\text{Perimeter}}{2}\)

\(\displaystyle \text{length}=\frac{\text{Perimeter}}{2}-\text{width}\)

Substitute in the given values for the width and perimeter to find the length.

\(\displaystyle \text{length}=\frac{36}{2}-10\)

Simplify.

\(\displaystyle \text{length}=18-10\)

Solve.

\(\displaystyle \text{length}=8\)

Now, recall how to find the area of a rectangle.

\(\displaystyle \text{Area}=\text{length}\times\text{width}\)

Substitute in the values of the length and width to find the area.

\(\displaystyle \text{Area}=10 \times 8\)

Solve.

\(\displaystyle \text{Area}=80\)

Example Question #591 : Basic Geometry

If the perimeter of a rectangle is \(\displaystyle 15\), and the width of the rectangle is \(\displaystyle 3\), what is the area of the rectangle?

Possible Answers:

\(\displaystyle 23\)

\(\displaystyle 22\)

\(\displaystyle 13.5\)

\(\displaystyle 23.5\)

Correct answer:

\(\displaystyle 13.5\)

Explanation:

Recall how to find the perimeter of a rectangle:

\(\displaystyle \text{Perimeter}=2(\text{length}+\text{width})\)

Since we are given the width and the perimeter, we can solve for the length.

\(\displaystyle \text{length}+\text{width}=\frac{\text{Perimeter}}{2}\)

\(\displaystyle \text{length}=\frac{\text{Perimeter}}{2}-\text{width}\)

Substitute in the given values for the width and perimeter to find the length.

\(\displaystyle \text{length}=\frac{15}{2}-3\)

Simplify.

\(\displaystyle \text{length}=7.5-3\)

Solve.

\(\displaystyle \text{length}=4.5\)

Now, recall how to find the area of a rectangle.

\(\displaystyle \text{Area}=\text{length}\times\text{width}\)

Substitute in the values of the length and width to find the area.

\(\displaystyle \text{Area}=3 \times 4.5\)

Solve.

\(\displaystyle \text{Area}=13.5\)

Example Question #181 : Quadrilaterals

If the perimeter of a rectangle is \(\displaystyle 100\), and the width of the rectangle is \(\displaystyle 12\), what is the area of the rectangle?

Possible Answers:

\(\displaystyle 471\)

\(\displaystyle 546\)

\(\displaystyle 330\)

\(\displaystyle 456\)

Correct answer:

\(\displaystyle 456\)

Explanation:

Recall how to find the perimeter of a rectangle:

\(\displaystyle \text{Perimeter}=2(\text{length}+\text{width})\)

Since we are given the width and the perimeter, we can solve for the length.

\(\displaystyle \text{length}+\text{width}=\frac{\text{Perimeter}}{2}\)

\(\displaystyle \text{length}=\frac{\text{Perimeter}}{2}-\text{width}\)

Substitute in the given values for the width and perimeter to find the length.

\(\displaystyle \text{length}=\frac{100}{2}-12\)

Simplify.

\(\displaystyle \text{length}=50-12\)

Solve.

\(\displaystyle \text{length}=38\)

Now, recall how to find the area of a rectangle.

\(\displaystyle \text{Area}=\text{length}\times\text{width}\)

Substitute in the values of the length and width to find the area.

\(\displaystyle \text{Area}=12 \times 38\)

Solve.

\(\displaystyle \text{Area}=456\)

Example Question #41 : How To Find The Area Of A Rectangle

If the perimeter of a rectangle is \(\displaystyle 60\), and the width of the rectangle is \(\displaystyle 12\), what is the area of the rectangle?

Possible Answers:

\(\displaystyle 188\)

\(\displaystyle 216\)

\(\displaystyle 96\)

\(\displaystyle 112\)

Correct answer:

\(\displaystyle 216\)

Explanation:

Recall how to find the perimeter of a rectangle:

\(\displaystyle \text{Perimeter}=2(\text{length}+\text{width})\)

Since we are given the width and the perimeter, we can solve for the length.

\(\displaystyle \text{length}+\text{width}=\frac{\text{Perimeter}}{2}\)

\(\displaystyle \text{length}=\frac{\text{Perimeter}}{2}-\text{width}\)

Substitute in the given values for the width and perimeter to find the length.

\(\displaystyle \text{length}=\frac{60}{2}-12\)

Simplify.

\(\displaystyle \text{length}=30-12\)

Solve.

\(\displaystyle \text{length}=18\)

Now, recall how to find the area of a rectangle.

\(\displaystyle \text{Area}=\text{length}\times\text{width}\)

Substitute in the values of the length and width to find the area.

\(\displaystyle \text{Area}=12 \times 18\)

Solve.

\(\displaystyle \text{Area}=216\)

Example Question #591 : Basic Geometry

If the perimeter of a rectangle is \(\displaystyle 36\), and the width of the rectangle is \(\displaystyle 9\), what is the area of the rectangle?

Possible Answers:

\(\displaystyle 99\)

\(\displaystyle 81\)

\(\displaystyle 108\)

\(\displaystyle 90\)

Correct answer:

\(\displaystyle 81\)

Explanation:

Recall how to find the perimeter of a rectangle:

\(\displaystyle \text{Perimeter}=2(\text{length}+\text{width})\)

Since we are given the width and the perimeter, we can solve for the length.

\(\displaystyle \text{length}+\text{width}=\frac{\text{Perimeter}}{2}\)

\(\displaystyle \text{length}=\frac{\text{Perimeter}}{2}-\text{width}\)

Substitute in the given values for the width and perimeter to find the length.

\(\displaystyle \text{length}=\frac{36}{2}-9\)

Simplify.

\(\displaystyle \text{length}=18-9\)

Solve.

\(\displaystyle \text{length}=9\)

Now, recall how to find the area of a rectangle.

\(\displaystyle \text{Area}=\text{length}\times\text{width}\)

Substitute in the values of the length and width to find the area.

\(\displaystyle \text{Area}=9 \times 9\)

Solve.

\(\displaystyle \text{Area}=81\)

Example Question #592 : Basic Geometry

If the perimeter of a rectangle is \(\displaystyle 16\), and the width of the rectangle is \(\displaystyle 7\), what is the area of the rectangle?

Possible Answers:

\(\displaystyle 7\)

\(\displaystyle 12\)

\(\displaystyle 6\)

\(\displaystyle 15\)

Correct answer:

\(\displaystyle 7\)

Explanation:

Recall how to find the perimeter of a rectangle:

\(\displaystyle \text{Perimeter}=2(\text{length}+\text{width})\)

Since we are given the width and the perimeter, we can solve for the length.

\(\displaystyle \text{length}+\text{width}=\frac{\text{Perimeter}}{2}\)

\(\displaystyle \text{length}=\frac{\text{Perimeter}}{2}-\text{width}\)

Substitute in the given values for the width and perimeter to find the length.

\(\displaystyle \text{length}=\frac{16}{2}-7\)

Simplify.

\(\displaystyle \text{length}=8-7\)

Solve.

\(\displaystyle \text{length}=1\)

Now, recall how to find the area of a rectangle.

\(\displaystyle \text{Area}=\text{length}\times\text{width}\)

Substitute in the values of the length and width to find the area.

\(\displaystyle \text{Area}=7 \times 1\)

Solve.

\(\displaystyle \text{Area}=7\)

Example Question #591 : Basic Geometry

If the perimeter of a rectangle is \(\displaystyle 10\), and the width of the rectangle is \(\displaystyle 1\), what is the area of the rectangle?

Possible Answers:

\(\displaystyle 6\)

\(\displaystyle 3\)

\(\displaystyle 5\)

\(\displaystyle 4\)

Correct answer:

\(\displaystyle 4\)

Explanation:

Recall how to find the perimeter of a rectangle:

\(\displaystyle \text{Perimeter}=2(\text{length}+\text{width})\)

Since we are given the width and the perimeter, we can solve for the length.

\(\displaystyle \text{length}+\text{width}=\frac{\text{Perimeter}}{2}\)

\(\displaystyle \text{length}=\frac{\text{Perimeter}}{2}-\text{width}\)

Substitute in the given values for the width and perimeter to find the length.

\(\displaystyle \text{length}=\frac{10}{2}-1\)

Simplify.

\(\displaystyle \text{length}=5-1\)

Solve.

\(\displaystyle \text{length}=4\)

Now, recall how to find the area of a rectangle.

\(\displaystyle \text{Area}=\text{length}\times\text{width}\)

Substitute in the values of the length and width to find the area.

\(\displaystyle \text{Area}=4 \times 1\)

Solve.

\(\displaystyle \text{Area}= 4\)

Example Question #591 : Basic Geometry

If the perimeter of a rectangle is \(\displaystyle 20\), and the width of the rectangle is \(\displaystyle 9\), what is the area of the rectangle?

Possible Answers:

\(\displaystyle 11\)

\(\displaystyle 8\)

\(\displaystyle 9\)

\(\displaystyle 10\)

Correct answer:

\(\displaystyle 9\)

Explanation:

Recall how to find the perimeter of a rectangle:

\(\displaystyle \text{Perimeter}=2(\text{length}+\text{width})\)

Since we are given the width and the perimeter, we can solve for the length.

\(\displaystyle \text{length}+\text{width}=\frac{\text{Perimeter}}{2}\)

\(\displaystyle \text{length}=\frac{\text{Perimeter}}{2}-\text{width}\)

Substitute in the given values for the width and perimeter to find the length.

\(\displaystyle \text{length}=\frac{20}{2}-9\)

Simplify.

\(\displaystyle \text{length}=10-9\)

Solve.

\(\displaystyle \text{length}=1\)

Now, recall how to find the area of a rectangle.

\(\displaystyle \text{Area}=\text{length}\times\text{width}\)

Substitute in the values of the length and width to find the area.

\(\displaystyle \text{Area}=9 \times 1\)

Solve.

\(\displaystyle \text{Area}=9\)

Example Question #41 : How To Find The Area Of A Rectangle

If the perimeter of a rectangle is \(\displaystyle 12\), and the width of the rectangle is \(\displaystyle 1\), what is the area of the rectangle?

Possible Answers:

\(\displaystyle 6\)

\(\displaystyle 7\)

\(\displaystyle 5\)

\(\displaystyle 4\)

Correct answer:

\(\displaystyle 5\)

Explanation:

Recall how to find the perimeter of a rectangle:

\(\displaystyle \text{Perimeter}=2(\text{length}+\text{width})\)

Since we are given the width and the perimeter, we can solve for the length.

\(\displaystyle \text{length}+\text{width}=\frac{\text{Perimeter}}{2}\)

\(\displaystyle \text{length}=\frac{\text{Perimeter}}{2}-\text{width}\)

Substitute in the given values for the width and perimeter to find the length.

\(\displaystyle \text{length}=\frac{12}{2}-1\)

Simplify.

\(\displaystyle \text{length}=6-1\)

Solve.

\(\displaystyle \text{length}=5\)

Now, recall how to find the area of a rectangle.

\(\displaystyle \text{Area}=\text{length}\times\text{width}\)

Substitute in the values of the length and width to find the area.

\(\displaystyle \text{Area}=5 \times 1\)

Solve.

\(\displaystyle \text{Area}=5\)

Learning Tools by Varsity Tutors