Question

how to use setsquares?

Answer 1

to draw parallel lines set square can be used. 1.position a edge on the set square  against a ruler and draw a line along one of the others edges
2.slide the set square into a new position while keeping the ruler fixed exactly at the same position
3.draw a line along the same edge that is used in point 1

Answer 2

to draw h1 and h2 in quadrilateral .
1. place ruler on daigonal .
2. place set square near 
<joining ruler> and and join to the end .< by moving set square with rulers balence > .
to draw height for figures eg : parallelogram .
with rulers support u can move the set square till the end that is point .
thats it :)
hope i helped :)