To understands what scale drawings are To be

To understands what scale drawings are. To be able to draw scale drawings To understand scale drawings.

What are scale drawings? Scale drawings are everywhere! Scale Drawings Vehicle design On Maps Footprints of houses Can you think of any more?

Scale drawings are SIMILAR to the original. To say that two objects are SIMILAR means that they are identical in shape, but not in size. In order for two shapes to be similar they must have the same angles and the sides must be in the same ratio. Example: Are these two shapes similar? Angles the same x 2 Sides have the same ratio – x 2 x 2 The two shapes are similar

2 cm 6 cm Are these pairs of shapes similar? 3 cm 50° 40° 6 m 40° 5 m 50° 70° 1. 5 1 m m 10 m 2 m 4 m 9 cm 60° 3 m

All scale drawings must have a scale written on them. Scales are usually expressed as ratios. Normally for maps and buildings the ratio: Drawing length: Actual length For maps the ratio is normally in the ratio: Map distance: Actual Distance Example: 1 cm : 100 cm The ratio 1 cm: 100 cm means that for every 1 cm on the scale drawing the length will be 100 cm in real life Example: 1: 10000 The ratio 1: 10000 means that the real distance is 10000 times the length of one unit on the map or drawing.

When you write a scale you must make sure that the units are the same. Example Simplify the scale 5 cm to 1 m 5 cm: 100 cm 1 cm: 20 cm Questions – Simplify the following scales 1) 10 cm: 2 m 1 cm: 20 cm 2) 5 mm: 10 cm 1 mm: 20 mm 3) 1 cm: 1 km 1 cm: 100000 cm Convert to the same units All ratios must be in the form 1: n. To make cm 1 cm then we must divide each side by 5

Task • Make a scale drawing of the building which you are renovating. To do this you need to measure EVERY room and the outside of the building. Do this in metres. • After you have measured the building you need to decide on a scale. Remember the whole drawing needs to fit on an A 3 piece of paper. (I advise you use the scale 1 cm: 100 cm) Using the scale 1 cm: 100 cm If a rectangular room measures 2. 5 m by 4 m then you have to convert both of the lengths into cm. (as this is the unit in the scale) 2. 5 m = 250 cm, 4 m = 400 cm If 100 cm in the actual drawing is represented by 1 cm then to get from the actual to the scale you need to divide by 100. 250 cm ÷ 100 = 2. 5 cm 400 cm ÷ 100 = 4 cm On the scale drawing this room would be 2. 5 cm by 4 cm