Confidential 2
1.Calculate 25% on 3500.
2. Convert 4.78 to percent
3. Write 7/8 as a percent
4. Write 90% as a fraction
5. If 2inches = 5 feet,4 inches = ___ feet
Warm up
Confidential 3
1. Ratio of two numbers X & Y(< >0) is X/Y (proper or improper fraction) written as X:Y.
A ratio should be expressed in its lowest form
2. In the ratio X : Y, the term X is called the antecedent and the term Y is called the consequent
3. All equivalent ratios can be expressed in one common ratio in its lowest form
4. Ratios are said to be in proportion when they are equivalent
Ratios
Lets review what we have learned in the last lesson
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Percent
What is a percent?
• The word percent comes from the Latin phrase per centum, which means per hundred.
• A percent is a ratio whose second term is 100.• Percent means parts per hundred. • we use the symbol % for percent. • Example: 60 %, 75 %, 90 %
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Converting fractions to percent
For converting fractions to percent follow the following steps:
• Divide the numerator of the fraction by its denominator
• Multiply the result by 100 (for that move the decimal point two places to the right)
• Put the % sign at the end of the result
Fractions and PercentFractions and Percent
Confidential 6
The decimal point separates the whole units on the
left from the decimal units on the right. • The numbers on the left side represent whole number
s such as ones, tens, hundreds, and thousands.
• The numbers on the right side of the point are the deci mal values. Those numbers represent values called
tenths, hundredths, thousandths, and so on.
What is a Decimal?
Decimal and Percent
Confidential 7
A rate is a ratio that is used to compare different kinds of quantities.
A unit rate describes how many units of the first type of quantity corresponds to one unit of the second type of quantity.
A unit price is a rate comparing the price of an item to its unit of measure.
To find the unit price divide the total cost by the number of items bought.
Ratio
Confidential 8
• A proportion is an equation that states that two ratios are equal .
• We can write proportions in two ways.
or 2:3 = 6:9 In a proportion, the product of the means
equals to the product of the extremes.
2 63 9
=
Scale and Proportion drawing
Confidential 9
• What are parallel lines?
• Parallel lines are two lines in a plane which do not meet even when produced indefinitely in either direction.
• Examples of parallel lines:
• opposite edges of a scale, railway lines, etc.
Lets Get Started
Confidential 10
• What are perpendicular lines?
• Perpendicular lines are lines that form right angles (90°) where they intersect.
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• Let us draw two parallel lines l and m and a transversal t which intersecting them at the points L and M respectively. Then eight angles are formed.
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Angles made by a transversal in parallel lines
• Interior angles• Exterior angles• Corresponding angles• Alternate Exterior angles• Alternate Interior angles
Note: Transversal is a line which intersects two or more lines in a plane at different points
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Interior Angles
• The angles whose arms include the line segment LM are called interior angles.
• Angle 3, angle 4, angle 5 and angle 6 are “Interior angles”.
• When a transversal cuts two parallel lines pairs, the sum of the interior angles on the same side of transversal is 180°
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Exterior Angles
• The angles whose arms do not include the line segment LM are called exterior angles.
• Angle 1, angle 2, angle 7 and angle 8 are “Exterior angles”.
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Corresponding Angles
Possible pairs of corresponding angles:
• Angle 1 and angle 5• Angle 2 and angle 6• Angle 4 and angle 8• Angle 3 and angle 7
When a transversal cuts two parallel lines pairs of corresponding angles are equal.
Confidential 16
Alternate Interior Angles
Possible pairs of alternate interior angles:
• Angle 3 and angle 5
• Angle 4 and angle 6
When a transversal cuts two parallel lines pairs of alternate interior angles are equal
Confidential 17
Alternate Exterior Angles
Possible pairs of alternate exterior angles:
• Angle 2 and angle 8
• Angle 1 and angle 7
Confidential 18
Pairs of alternate interior angles are equal Pairs of corresponding angles are equal The sum of the interior angles on the same
side of transversal is 180°
Rule
If a transversal cuts two lines such that any one of the following conditions hold:
Then the two lines are parallel.
Confidential 19
Example 1• In the given figure, l || m, find the values of x and y.
• When a transversal cuts two parallel lines pairs of alternate interior angles are equal.
So x = 40° ( x and 40° are alternate interior angles) y + 40° = 180° ( t is a straight line) y = 180° - 40° (subtract 40 on both the sides) y = 140°
Confidential 20
Example 2
• In the given figure, l || m and p || q, find the values of a, b, c and d.
c = 80° ( Vertically opposite angles) c = d (l || m so Corresponding angles are equal) d = 80° ( c =d and c = 80° proved above) b = c (p || q so Corresponding angles are
equal) b = 80° ( b =c and c = 80° proved above) similarly we can prove a = b and then a = 80°
Confidential 21
Your Turn
In the given figure 1, AB || CD and AC || BD
1) Find x
2) Find y In the given figure 2, l || m
3) Find x
4) Find y
5) Find z
6) Find w
Figure 1
Figure 2
Confidential 22
Your Turn
In the given figure, l || m
7) Name a pair of corresponding angles.
8) Name a pair of alternate interior angles.
9) What is the sum of angles 4 and 5?
10) If angle 4 = 100° , find angle 5.
Figure 1
Confidential 23
Confidential 24
Let us play a game
Click here to play
Confidential 25
1. In the given figure, AB || CD and CD || EF.
Is AB || EF? Give reasons.
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2. In the given figure, PQ || RS. Find the value of x.
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3. In the given figure, a transversal t cuts two lines l and m such that angle 2 = 65° and angle 8 = 65°. Are the lines parallel?
Confidential 28
Parallel lines are two lines in a plane which do not meet even when produced indefinitely.
When a transversal cuts two parallel lines pairs, the sum of the interior angles on the same side of transversal is 180°.
When a transversal cuts two parallel lines pairs of corresponding angles are equal.
When a transversal cuts two parallel lines pairs of alternate interior angles are equal.
Confidential 29
Review
Two lines are parallel if any one of the following conditions hold:
• Pairs of alternate interior angles are equal.
• Pairs of corresponding angles are equal.• The sum of the interior angles on the
same side of transversal is 180°
Confidential 30
Great Lesson Today!
Be sure to practice well