Question

What are the two arms are in $\angle PRQ$:
A) $\overrightarrow {PR} $ and $\overrightarrow {RQ} $
B) $\overrightarrow {RP} $ and $\overrightarrow {RQ} $
C) $\overrightarrow {QR} $ and $\overrightarrow {QP} $
D) None of the above

Answer 1

 Hint: Draw an angle and name it as $\angle PRQ$ and fix the middle letter $R$ at the vertex of the letter and then identify the arms of the angle.

Complete step-by-step answer:
Given: $\angle PRQ$
Draw an angle with vertex $R$.

Now, as we have to name the complete angle, then we need to identify the first letter of the angle, that is $P$, then name the top of the vertical line as $P$.

Now, put the last letter, that is $Q$ at the end of the horizontal line on the right side.

Now, identify the name of the vertical side of the angle, that is $\overrightarrow {PR} $.
As one arm is identified, now we need to identify the other arm, start from point $R$ and go along with the horizontal side to the end on right, where we will reach at the point $Q$, so the other arm is $\overrightarrow {RQ} $.
So the arms of $\angle PRQ$ are $\overrightarrow {PR} $ and $\overrightarrow {RQ} $.
To find arms of any angle, we have to go with the order of letters mentioned in the angle, for example $\angle ABC$, so by following the order of letters mentioned in the angle, $\overrightarrow {AB} $ should be the arm, not $\overrightarrow {BA} $. Similarly $\overrightarrow {BC} $ will be the second arm, not $\overrightarrow {CB} $.
As a result $\overrightarrow {PR} $ and $\overrightarrow {RQ} $ will be the arm of $\angle PRQ$, not $\overrightarrow {RP} $ and $\overrightarrow {QR} $.
Hence the correct option is A.

Note: Arms can lie on any side, like arms can be on below or left side, but the position of the middle letter in the letter is always fixed, that letter will always lie on the vertex.