Final answer:
The degree of the angle indicated in bold cannot be determined without additional context. However, the answers to the numbered questions provided are 45° for the optimal projectile angle, 0° or 90° for a projectile range of zero, and that 1 radian equals approximately 57.3°.
Step-by-step explanation:
The question seems fragmented and provides numerical and literal options that are not clearly associated with a specific question or angle measurement, making it difficult to provide a single accurate response. However, if we were to answer questions based on the information provided:
- For question 86, the optimum angle at which a projectile should be launched to cover the maximum distance is 45°.
- For question 69, the angle at which a projectile's range is zero is either 0° or 90°.
- For question 23 in section 6.1 Angle of Rotation and Angular Velocity, 1 radian is approximately 57.3° in degrees.
To find the measure of the angle indicated in bold, additional context is required since the statement is unclear and does not specify which angle is to be found.