In the diagram, PQRS is a trapezoid with an area of 12. RS is twice the length of PQ. What is the area of △PQS?
Note that triangle PQS has the same height as triangle QRS
And triangles under the same height are to each other as their bases...
So....since RS = 2PQ.....then the area of triangle QRS = 2 area of triangle PQS
So area of QRS + area of PQS = 12 substituting......we have
area [ 2PQS + PQS ] = 12
area [ 3PQS ] = 12 divide both sides by 3
area PQS = 4