Shape and Space CONSTRUCTION

STRONG TRIANGLES Triangles are very important. Shapes that are made from triangles are usually very strong. Many structures like bridges, pylons and towers are built using triangles.

DRAWING A TRIANGLE Draw triangle ABC AB = 7cm, Angle A = 36° Angle B = 58° 36° 58° 7cmAB C What size is angle C? = 94° Angle C = 180 – 94 = 86° Or you could measure angle C using the protractor

EXERCISES 1. Draw Triangle LMN a)LM = 8cm, Angle L = 47° Angle M = 32° b) What is angle N? 2. Draw Triangle PQR a)PQ = 6cm, Angle P = 28° Angle Q = 78° b) What is angle R? 3. Draw Triangle XYZ a)XY = 6.5cm Angle X = 56° Angle Y = 43° b) Beth yw ongl Z?

BISECT AN ANGLE It’s possible to bisect an angle (in half) using a compass. Step 1 : Open the compass to any distance. You must keep the compass at this distance.

BISECT AN ANGLE It’s possible to bisect an angle (in half) using a compass. A B Step 2 : Put the compass on the corner of the angle and draw a small arc which cross both arms of the angle. Label these points A and B.

BISECT AN ANGLE It’s possible to bisect an angle (in half) using a compass. A B Step 3 : Put the compass on point A and repeat step 2. Then do the same with point B.

BISECT AN ANGLE It’s possible to use the same method to draw a perfect circle within a triangle. Notice that the circle touches the three sides of the triangle. REMEMBER TO KEEP THE COMPASS AT THE SAME DISTANCE

BISECT AN ANGLE