Solve each problem using a system of equations in two variables. See Example 6. Find two numbers whose ratio is 4 to 3 and are such that the sum of their squares is 100.
Table of contents
- 0. Review of Algebra4h 18m
- 1. Equations & Inequalities3h 18m
- 2. Graphs of Equations1h 43m
- 3. Functions2h 17m
- 4. Polynomial Functions1h 44m
- 5. Rational Functions1h 23m
- 6. Exponential & Logarithmic Functions2h 28m
- 7. Systems of Equations & Matrices4h 5m
- 8. Conic Sections2h 23m
- 9. Sequences, Series, & Induction1h 22m
- 10. Combinatorics & Probability1h 45m
7. Systems of Equations & Matrices
Two Variable Systems of Linear Equations
Problem 68
Textbook Question
Solve each problem. Find the radius and height (to the nearest thousandth) of an open-ended cylinder with volume 50 in.3 and lateral surface area 65 in.2.

Verified step by step guidance1
Recall the formulas for the volume and lateral surface area of an open-ended cylinder. The volume \(V\) is given by \(V = \pi r^2 h\), where \(r\) is the radius and \(h\) is the height. The lateral surface area \(A\) (without the top and bottom) is \(A = 2 \pi r h\).
Write down the system of equations using the given values: \(\pi r^2 h = 50\) and \$2 \pi r h = 65$.
From the lateral surface area equation \$2 \pi r h = 65\(, solve for \)h\( in terms of \)r\(: \)h = \frac{65}{2 \pi r}$.
Substitute the expression for \(h\) into the volume equation: \(\pi r^2 \left( \frac{65}{2 \pi r} \right) = 50\). Simplify this equation to get an equation in terms of \(r\) only.
Solve the resulting equation for \(r\), then use the value of \(r\) to find \(h\) using the expression \(h = \frac{65}{2 \pi r}\). Round both \(r\) and \(h\) to the nearest thousandth.
Verified video answer for a similar problem:This video solution was recommended by our tutors as helpful for the problem above
Video duration:
6mPlay a video:
Was this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Volume of a Cylinder
The volume of a cylinder is calculated using the formula V = πr²h, where r is the radius and h is the height. This formula represents the amount of space inside the cylinder and is essential for relating the radius and height to the given volume.
Lateral Surface Area of an Open Cylinder
The lateral surface area of an open cylinder (without top and bottom) is given by A = 2πrh. This formula calculates the area of the curved surface, which helps establish a relationship between the radius and height based on the given surface area.
Recommended video:
Guided course
Systems of Inequalities
Solving Systems of Nonlinear Equations
Finding the radius and height requires solving two equations simultaneously: one for volume and one for lateral surface area. This involves techniques such as substitution or elimination to solve nonlinear equations involving π, r, and h.
Recommended video:
Guided course
Solving Systems of Equations - Substitution
Watch next
Master Introduction to Systems of Linear Equations with a bite sized video explanation from Patrick
Start learningRelated Videos
Related Practice
Textbook Question
414
views
