Answer: The hotel doorman for opening the door for him
Step-by-step explanation: that one was tricky
Number 21 is the first answer a.) 8
Answer:
AD~CB or ABD~BCD OR AB~CD
Answer: 
Step-by-step explanation:
We need to apply the following identity:

Then, applying this, you know that for
:

We need to remember that:
and 
Therefore, we need to substitute these values into
.
Then, you get:


