In a two-dimensional tug-of-war, Alex, Betty, and Charles pull horizontally on an automobile tire at the angles shown in the overhead view of Fig. 5-33. The tire remains stationary in spite of the three pulls. Alex pulls withe force Fa of magnitude 220N and Charles pulls with force Fc of magnitude 170N. Note that the direction of Fc is not given. What is the magnitude of Betty's force Fb?

The "angles shown in the overhead view" are needed to answer your question. You have not provided them.

Vector Fc is the equilbrant (negative resultant) of Fa and Fb

To find the magnitude of Betty's force (Fb), we need to analyze the equilibrium condition of the forces involved. In a two-dimensional tug-of-war, the forces can be resolved into their horizontal and vertical components. Since the tire remains stationary, the sum of all the horizontal components of the forces must equal zero, and the sum of all the vertical components of the forces must also equal zero.

Let's break down the given information to find the unknown magnitude of Betty's force (Fb):

1. Alex's force: Fa = 220N (magnitude)
- We know the magnitude of Alex's force, but we don't know the angle at which he pulls. Therefore, we cannot determine its horizontal or vertical components yet.

2. Charles's force: Fc = 170N (magnitude)
- The direction of Charles's force is not given. Therefore, we cannot determine its horizontal or vertical components at this point.

3. Betty's force: Fb = ?
- We need to find the magnitude of Betty's force.

To proceed, we need to know the direction of Charles's force (angle), which is not provided in the question. Without the angle, we cannot determine the components of his force and, thus, cannot solve for the magnitude of Betty's force (Fb).

So unfortunately, based on the given information, we cannot determine the magnitude of Betty's force (Fb) because the angle of Charles's force (Fc) is not provided.