Today's Class - Feb 2nd

What means to be proportional? What means a ratio? Those are some of the questions we addressed today in class. A ratio is a comparison of two quantities, that can be represented by: 5 to 7, 5 : 7 or simply as a fraction 5/7. When we have two equivalent fractions we say that they are proportional to each other. Remember that to solve a proportion (2 fractions equal to each other) we use cross multiplication. But what happens when we have 3 equivalent fractions written together as in the following example?



Just select two of them (by ignoring the third one) and solve it normally. For this you could use the first two fractions to solve for x, and easily select the first and third fractions to solve for y.

We also explored the idea of two images being proportional to each other, as in the following diagram:

Through it we can observe that the corresponding sides have the same ratio. In other words the corresponding sides are proportional.
You will use these ideas to do the homework: page 342 # 18, 20, 22, 26, 28, 29, 32, 33 and 41 to 44.