Section 7.1 and 7.2 Ratios and Proportions.

Similar vs. Congruent Talk with your partner about the difference between similar and congruent figures. Congruent means same size and same shape Similar means same shape and proportionate size. What stays the same in a similar figure and what changes?

Ratio The ratio of one number to another is the quotient when the 1st number is divided by the second. Expressed in simplest form. Must be expressed as whole numbers Remember…can’t divide by 0! Example: The ratio of 8 to 12 is 8/12=2/3 or 8:12=2:3 Example: The ratio of ½ to ¼ is ½ : ¼ so 2:1

Practice! a. Find the ratio of AE to BE. b. Find the ratio of the largest angle of triangle ACE to the smallest angle of triangle DBE. A D 60° 10 60° 30° E C 5x 30° B

Do the Next 2 ALONE!! Do the next 2 problems on your notes alone. Compare your answers with your partner. Get in groups and do the problems from the textbook!

Proportions A proportion is an equation that states that 2 ratios are equal. In , a and d are known as extremes and b and c are called the means.

Properties If Then… 1.ad=bc 2. 3. 4. 5. If a = c = e = … b d f 3. 4. 5. If a = c = e = … b d f Then a + c + e + … = a = … b + d + f + … b

Practice If what other equations can be made?   a. b. c. d.

Do the next 2 Alone Do the next 2 problems alone. Grab a worksheet and work on this in partners!! THIS WILL BE COLLECTED AND GRADED!!

Homework Pg. 243 #7-13 (odds); Pg. 244 #21-35 (odds);