Question

in the triangular pyramid shown below, which lines are skew?
image of triangular pyramid with vertices r, t, s, u. below the image are four multiple - choice options: (overleftrightarrow{rt}) and (overleftrightarrow{su}), (overleftrightarrow{su}) and (overleftrightarrow{tu}), (overleftrightarrow{st}) and (overleftrightarrow{su}), (overleftrightarrow{rt}) and (overleftrightarrow{tu})

Explanation:

Step1: Define skew lines

Skew lines are non-parallel, non-intersecting lines in 3D space.

Step2: Check each option

• $\overrightarrow{RT}$ and $\overrightarrow{SU}$: No common points, not parallel → skew.
• $\overrightarrow{SU}$ and $\overrightarrow{TU}$: Intersect at U → not skew.
• $\overrightarrow{ST}$ and $\overrightarrow{SU}$: Intersect at S → not skew.
• $\overrightarrow{RT}$ and $\overrightarrow{TU}$: Intersect at T → not skew.

Answer:

A. $\overrightarrow{RT}$ and $\overrightarrow{SU}$