Mathematical+Reflections+p.58+2011

3/21/11 S.L

Mathematical Reflection 4 = Big Idea: Many things in the world are mathematically similar and we can use this to understand and describe the world around us. = = Essential Question: In what types of situations do I need to use my similarity ideas so that I can solve them? =

//1. How can you decide whether two figures are similar?// I can decide if the two figures are similar by determining the angle measurement and the side lengths (scale factor) 2//. What does a scale factor between two similar figures tell you about the relationship between the length and area measures of a small figure.// The scale factor gives me a ratio that I can work with to figure out any length, width and the area of any shape. //3. If the scale factor from a small figure to a large figure is given as a percent, how can you find the side lengths of a large figure from a small figure?// You can multiply the percentage (divided into fractions) with x so you get y our height/ width (side lengths) //4. Decide whether each pair of rectangles below is similar. If the rectangles are similar, give the scale factor from the rectangle on the left to the rectangle on the right. If they aren't explain why.// a.) no, because the side lengths don't have a scale factor b.) yes, because there is a proper scale factor and they all have a 90 degree right angles.

Summary In this investigation we used porportions to estimate the height of someone in a picture, and we used scale factors to see if there were similar shapes, and percentages to match the scale factor and we used the scale factors in the investigation to basically find out the similar shapes and their width and height.