Constructions 1 Follow these instructions to accurately construct a triangle with sides 7 cm, 8 cm and 9 cm. 8 cm 7 cm 9 cm a Use a ruler to draw the 9 cm side accurately. b The 7 cm side starts at the left-hand end of this line. Open your compasses to exactly 7 cm and draw an arc from the left-hand end of the line. c Open your compasses to exactly 8 cm and draw an arc from the other end. d Use the point where the arcs cross to create the finished triangle. 8 cm 7 cm 9 cm 2 Construct this triangle. 9 cm 4 cm 9 cm 9 cm 7 cm 8 cm 3 Construct a scale diagram of this triangle. Use the scale 1 cm to 1 m. 8.2 m 8.2 m Q4 Strategy hint 6.8 m 10 cm 4 Draw and construct an accurate net of this triangular prism. 7 cm 7 cm Sketch the net and write the measurements on it. Make an accurate drawing of the rectangles using a ruler and protractor. Construct the triangles using compasses. 7 cm 5 Draw a line 14 cm long. Follow these instructions to construct the perpendicular bisector of this line. a Draw the line. Open your compasses to more than half the length of the line. b Draw the first arc. c Draw the second arc. 14 cm Q5 Strategy hint Remember this diagram. d Draw the perpendicular bisector. Q5 hint Check by measuring that the angle is 90° and the line is cut in half. 6 Use a ruler to draw a line 11.5 cm long. Construct the perpendicular bisector of this line. Unit 7 Constructions and loci 164