Math Problem Statement

Vectors A and B have equal magnitudes of 4.75. If the sum of A and B is the vector 7.59j, determine the angle between A and B.

Solution

Given two vectors A\mathbf{A} and B\mathbf{B}, both having equal magnitudes of 4.75, and their sum is A+B=7.59j^\mathbf{A} + \mathbf{B} = 7.59 \hat{j}, we are tasked with finding the angle θ\theta between these two vectors.

Step 1: Express the vectors

The vectors A\mathbf{A} and B\mathbf{B} can be written in terms of their components:

A=4.75(cosθ1i^+sinθ1j^)\mathbf{A} = 4.75 (\cos \theta_1 \hat{i} + \sin \theta_1 \hat{j}) B=4.75(cosθ2i^+sinθ2j^)\mathbf{B} = 4.75 (\cos \theta_2 \hat{i} + \sin \theta_2 \hat{j})

Since both vectors have the same magnitude, let's assume without loss of generality that one vector is at an angle θ/2\theta/2 above the horizontal and the other is at an angle θ/2-\theta/2 below the horizontal:

A=4.75(cos(θ/2)i^+sin(θ/2)j^)\mathbf{A} = 4.75 (\cos(\theta/2) \hat{i} + \sin(\theta/2) \hat{j}) B=4.75(cos(θ/2)i^sin(θ/2)j^)\mathbf{B} = 4.75 (\cos(\theta/2) \hat{i} - \sin(\theta/2) \hat{j})

Step 2: Sum of the vectors

The sum A+B\mathbf{A} + \mathbf{B} will have its i^\hat{i}-components cancel out because of symmetry, leaving only the j^\hat{j}-components:

A+B=4.75sin(θ/2)j^+4.75sin(θ/2)j^=9.5sin(θ/2)j^\mathbf{A} + \mathbf{B} = 4.75 \sin(\theta/2) \hat{j} + 4.75 \sin(\theta/2) \hat{j} = 9.5 \sin(\theta/2) \hat{j}

Step 3: Set the sum equal to the given value

We are given that the sum of the vectors is 7.59j^7.59 \hat{j}, so we can set the magnitudes of the j^\hat{j}-components equal:

9.5sin(θ/2)=7.599.5 \sin(\theta/2) = 7.59

Step 4: Solve for θ/2\theta/2

Solving for sin(θ/2)\sin(\theta/2):

sin(θ/2)=7.599.5=0.7989\sin(\theta/2) = \frac{7.59}{9.5} = 0.7989

Now, take the inverse sine to find θ/2\theta/2:

θ/2=sin1(0.7989)53.01\theta/2 = \sin^{-1}(0.7989) \approx 53.01^\circ

Thus,

θ2×53.01=106.02\theta \approx 2 \times 53.01^\circ = 106.02^\circ

Final Answer:

The angle between vectors A\mathbf{A} and B\mathbf{B} is approximately 106.02\boxed{106.02^\circ}.

Would you like further details or clarifications?

Related Questions:

  1. How do you find the dot product of two vectors when their angle is known?
  2. What is the geometric interpretation of two vectors with the same magnitude?
  3. How do you break down vectors into components for different coordinate systems?
  4. What happens when two vectors have an angle of 9090^\circ between them?
  5. How does the vector sum change if the angle between the vectors is zero?

Tip:

When adding vectors geometrically, always break them down into components, as it simplifies the process of solving vector equations.

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Math Problem Analysis

Mathematical Concepts

Vector Addition
Trigonometry

Formulas

Vector addition formula: A + B = (Ax + Bx)i + (Ay + By)j
Trigonometric function: sin(θ)

Theorems

Inverse Sine Theorem
Pythagorean Identity

Suitable Grade Level

Grade 11-12 or early college