We can solve this by looking at pairs that equal 60. 6 and 10 get to 60 when multiplied. Let's see if it fits in as a perimeter. 12+20=32 So the width and length of the room is 6 meters and 10 meters.
You can draw a general triangle to start a proof unless you are given any specific qualities the triangle must have the triangle doesn't have to be draw to scale.