 Hello and welcome to the session. In this session we discussed the following question which says in the given figure pq is equal to 1 cm, qr is equal to 3 cm and sr is equal to 12 cm, find cot phi. So, we are given this figure. In this we are given the lengths of pq, qr and sr and we have to find cot phi. So, let's see the solution. Let's see what all is given to us. We are given pq equal to 4 cm, qr equal to 3 cm, sr equal to 12 cm and we have to find cot phi. So, as you can see that angle prs is given as 90 degrees. So triangle prs is right angle triangle. Also we have angle pqr is also of measure 90 degrees. So triangle pqr is also right angle triangle. Now, first of all we consider in right triangle pqr we would apply the Pythagoras theorem. So, we have pr square is equal to pq square plus qr square this is by the Pythagoras theorem. Now, we know that pq is equal to 4 cm and qr is equal to 3 cm. So, we substitute these values to get the value of pr that is we have pr square is equal to 4 square plus 3 square. So, pr square is equal to 16 plus 9 equal to 25. This means pr is equal to square root 25 that is equal to 5 cm. So, we got pr equal to 5 cm. Now, consider the triangle prs in this cot phi is equal to base upon perpendicular base is sr upon the perpendicular that is pr, sr is of measure 12 cm and pr is of measure 5 cm. So, we get cot phi is equal to 12 upon 5. This is our final answer. This completes the session. Hope you have understood the solution of this question.