Download 7.1 Ratio and Proportion

7.1 Ratio and Proportion
Ratio
• Ratio- compares two numbers by division.
Can be written as “a to b, a:b, or a
b
• In a ratio, the denominator of the fraction
cannot be zero because division by zero is
undefined.
Example
• Write a ratio expressing the slope of l.
Example
• Given that two points on m are C(–2, 3) and
D(6, 5), write a ratio expressing the slope of
m.
Example
• The ratio of the side lengths of a triangle is
4:7:5, and its perimeter is 96 cm. What is the
length of the shortest side?
Example
• The ratio of the angle measures in a triangle is
1:6:13. What is the measure of each angle?
Definitions
• Proportion: an equation stating that two
ratios are equal.
a c

b d
• Means: b and c values
• Extremes: a and d values
Cross Products Property
Examples
• Solve the Proportion.
1)
2)
3)
4)
Examples
• Solve the Proportion.
5)
6)
Properties of Proportions
Examples
• Given that 18c = 24d, find the ratio of d to c in
simplest form.
• Given that 16s = 20t, find the ratio t:s in
simplest form.
Example
• Marta is making a scale drawing of her
bedroom. Her rectangular room is 12 feet
wide and 15 feet long. On the scale drawing,
the width of her room is 5 inches. What is the
length?