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Today’s Vocabulary Ratio – a comparison of two things – a/b….. a:b Extended ratio – a comparison of three or more things – a:b:c Proportion – two ratios set equal to each other – a/b = c/d Extended proportion – three or more ratios set equal to each other: a/b = c/d = m/n = x/y Extremes – the first and last terms in a proportion A/b = c/D A and D are the extremes Means – the middle terms in a proportion a/B = C/d B and C are the means Cross Products Property – multiplying the means and extremes to solve an equation. Remember you can only do this when you have a proportion.

acac ratio extended ratio or a:c a:c:x:y

a b c d = proportion extended proportion a b x c d y ==

a b c d a b c d = a b c d means extremes =

a b c d = Cross Products property ad = bc

Similar figures – things that have the same shape but are generally a different size. Similar polygons – polygons that have the same shape but are a different size Scale - a ratio that compares each length in a scale drawing. Scale factor - The ratio of corresponding linear measurements of two similar figures. Scale drawing - A drawing where all lengths are proportional to their corresponding actual lengths. more of Today’s Vocabulary

similar figures similar polygons

scale factor scale drawing AC = AT = CT GO GD OD 16 = 12 = = 4 = 4 The scale factor is 4 Every 1 mm on this drawing, corresponds to 10 mm on the real horse.

let’s brush up and practice Write the ratio of the first measurement to the second measurement. 1.length of car: 14 ft 10 in. length of model car: 8 in 2.weight of car: 2900 lb weight of model car: 8 oz 3. There are 238 juniors at Torrington High School. The ratio of girls to boys in the junior class is 3:4. How many juniors are girls? How many are boys? Convert to inches: (14)(12) + 10 = : 8 convert : 8 oz = ½ lb =.5 lb 2900:.5 3x + 4x = 238x = 34 There are 102 girls and 136 boys in the junior class.

3 = x 5 25 x = 15 x = x = 18 x - 2 = x = 8

Your assignment ♥ 7-1 Practice worksheet Don’t do 15 – 18 ♥ 7-1 Reteach worksheet Don’t do