Similar triangles If I take a triangle that is 3cm x 4cm x 5cm and hold it in front of a light. I can project a much larger image on a distant wall 3m x 4m x 5m These triangle are similar, so their measurements are proportional .
Similar triangles If I move the projector closer to the wall the image on the wall shrinks But it will still be proportional 15cm x 20 cm x 25 cm The angles of the two triangles are equal If I cut the base of the large triangle in half with a line parallel to the left side The right side of the old triangle will create a new similar triangle 7.5cm x 10cm x 12.5cm Each of these measurement is ½ the previous measurements The ratio between the two triangles is 1:2 Another way to express the ratio is ½ .
Similar triangles We can simplify many seemingly difficult questions simply by discovering similarity of triangles When we know the ratio or recognize it easily we have solved 90% of the problem. A 6ft man casts 5 ft shadow next to a flagpole that is casting a 20 foot shadow. How tall is the flagpole ? 6/5 equals x/20 Two easy ways to solve I multiplied 5 x 4 to get 20 Do the same for six (6 x 4 = 24) Another method . ? 6 5 20
Similar triangles Questions from Triand MCAS test
Similar triangles Questions from Triand MCAS test