Textbook Question
Two forces act on a point in the plane. The angle between the two forces is given. Find the magnitude of the resultant force.
forces of 250 and 450 newtons, forming an angle of 85°
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Ch. 7 - Applications of Trigonometry and Vectors
Lial12th EditionTrigonometryISBN: 9780136552161
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Table of contents
- Ch. R - Algebra Review381
- Ch. 1 - Trigonometric Functions188
- Ch. 2 - Acute Angles and Right Triangles168
- Ch. 3 - Radian Measure and The Unit Circle155
- Ch. 4 - Graphs of the Circular Functions100
- Ch. 5 - Trigonometric Identities238
- Ch. 6 - Inverse Circular Functions and Trigonometric Equations158
- Ch. 7 - Applications of Trigonometry and Vectors148
- Ch. 8 - Complex Numbers, Polar Equations, and Parametric Equations15
Chapter 8, Problem 25
Use the parallelogram rule to find the magnitude of the resultant force for the two forces shown in each figure. Round answers to the nearest tenth.
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Verified step by step guidance1
Identify the magnitudes of the two forces and the angle between them from the figure. Let's denote the forces as \( F_1 \) and \( F_2 \), and the angle between them as \( \theta \).
Recall the parallelogram rule states that the magnitude of the resultant force \( R \) can be found using the formula:
\[ R = \sqrt{F_1^2 + F_2^2 + 2 F_1 F_2 \cos(\theta)} \]
Substitute the known values of \( F_1 \), \( F_2 \), and \( \theta \) into the formula. Make sure the angle \( \theta \) is in degrees or radians consistent with your calculator settings.
Calculate the value inside the square root step-by-step: first square each force, then calculate the product \( 2 F_1 F_2 \cos(\theta) \), and finally sum all these terms.
Take the square root of the sum to find the magnitude of the resultant force \( R \). Round your answer to the nearest tenth as requested.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Parallelogram Rule for Vector Addition
The parallelogram rule is a graphical method to add two vectors. By placing the vectors tail-to-tail, a parallelogram is formed, and the diagonal from the common tail point represents the resultant vector. The magnitude and direction of this diagonal give the combined effect of the two forces.
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Adding Vectors Geometrically
Vector Magnitude Calculation Using Law of Cosines
When two vectors form an angle, the magnitude of their resultant can be found using the law of cosines: R = √(A² + B² + 2AB cos θ), where A and B are magnitudes of the vectors and θ is the angle between them. This formula helps compute the resultant force without graphical methods.
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Rounding and Precision in Final Answers
After calculating the magnitude of the resultant force, it is important to round the answer to the specified precision, here to the nearest tenth. Proper rounding ensures clarity and consistency in reporting results, especially in applied problems involving measurements.
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Related Practice
Textbook Question
Write each vector in the form 〈a, b〉. Write answers using exact values or to four decimal places, as appropriate.
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Textbook Question
Solve each triangle. See Examples 2 and 3.
a = 965 ft, b = 876 ft, c = 1240 ft
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Textbook Question
Solve each triangle ABC that exists.
A = 38° 40', a = 9.72 m, b = 11.8 m
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Textbook Question
Solve each triangle ABC.
B = 42.88°, C = 102.40°, b = 3974 ft
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Textbook Question
Solve each triangle. See Examples 2 and 3.
a = 42.9 m, b = 37.6 m, c = 62.7 m
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