Chapter 2.7, Problem 16PSC

To determine

The fault in Fool’s proof is to be found

Answer to Problem 16PSC

The method of substitution of CB by AB can’t work unless we know that CD and AB are two parallel lines

Explanation of Solution

Given information : The following information is given

  $\overrightarrow{AB}\perp \overrightarrow{PR}$

  $\overrightarrow{AB}\cong \overrightarrow{CD}$

Now, we know that $\angle CDB$ is not known

Thus, method of substitution of CB by AB can’t work unless we know that CD and AB are two parallel lines

Hence, fault in the method is known