Lesson 4 -2 Proportions & Similar Figures Objective: To find missing measures of similar figures and to use similar figures when measuring indirectly.
Why is this important? • To apply proportions when finding distances represented on maps.
Vocabulary • Similar figures – have the same shape but not • • • necessarily the same size. Symbol for similar – “ ~ “ Scale drawing – an enlarged or reduced drawing that is similar to an actual object or place. Scale – the ratio of a distance in the drawing to the corresponding actual distance.
Example 1, page 190 • / FGH ~ / KLM. Find LM. K F 2 4 32 L G H 20 M
Example 2, page 191 • A) A tree casts a 26 -ft. shadow. A boy standing nearby casts a 12 -ft shadow. His height is 4. 5 ft. How tall is the tree?
Example 2, continued • B) A house casts a 56 -ft shadow. A girl standing nearby casts 7. 2 -ft shadow. Her height is 5. 4 ft. What is the height of the house?
Real World Problem Solving Example 3, page 191 • A) On the map given in the book, measure the map distance from Grant to Gifford. Find the actual distance.
Example 3, continued • B) If another map showed the distance from Valkaria to Wabasso but had a scale of 1 inch: 5 miles, what would the map distance be between the two locations?
Summary • How do I use proportions to find missing measures of similar figures? • How do I find actual distances?
Assignment page 192 #1 -20 all, 21 – 33 odd, 41 -48 all
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