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09 maths key notes ch 09 areas of parallelograms and triangles(1)

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Key Notes
Chapter 25
Areas of Qogles
1. Figures on the same Base and Between the same Parallels
2. Parallelograms on the same Base and between the same Parallels
3. Triangles on the same Base and between the same Parallels
1.
"It was so great to hear from you today and it was such
"This is going to sound funny and a little strange, but
had just a couple of days ago. I'd love to get together
if you're up for a cup of coffee," he continued, laying
planning for years.
weird timing," he said.
you were in a dream I
and tell you about it
the trap he'd been
2.
3.
She considered the birds to be her friends. She'd put out food for them each
morning and then she'd watch as they came to the feeders to gorge themselves
for the day. She wondered what they would do if something ever happened to her.
Would they miss the meals she provided if she failed to put out the food one
morning?
4.
5.
His parents continued to question him. He didn't know what to say to them
since they refused to believe the truth. He explained again and again, and
they dismissed his explanation as a figment of his imagination. There was no
way that grandpa, who had been dead for five years, could have told him where
the treasure had been hidden. Of course, it didn't help that grandpa was
roaring with laughter in the chair next to him as he tried to explain once
again how he'd found it.
6.
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Key Notes
7.
There were only two ways to get out of this mess if they all worked together.
The problem was that neither was all that appealing. One would likely cause
everyone a huge amount of physical pain while the other would likely end up
with everyone in jail. In Sam's mind, there was only one thing to do. He threw
everyone else under the bus and he secretly sprinted away leaving the others
to take the fall without him.
8.
9.
Sometimes that's just the way it has to be. Sure, there were probably other
options, but he didn't let them enter his mind. It was done and that was that.
It was just the way it had to be.
10.
11.
Devon couldn't figure out the color of her eyes. He initially would have
guessed that they were green, but the more he looked at them he almost wanted
to say they were a golden yellow. Then there were the flashes of red and
orange that seemed to be streaked throughout them. It was almost as if her
eyes were made of opal with the sun constantly glinting off of them and
bringing out more color. They were definitely the most unusual pair of eyes
he'd ever seen.
12.
13.
The computer wouldn't start. She banged on the side and tried again. Nothing.
She lifted it up and dropped it to the table. Still nothing. She banged her
closed fist against the top. It was at this moment she saw the irony of trying
to fix the machine with violence.
14.
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Key Notes
15.
They say you only come to peace with yourself when you know yourself better
than those around you. Derick knew nothing about this. He thought he had found
peace but this was an illusion as he was about to find out with an unexpected
occurrence that he actually knew nothing about himself.
16.
17.
"What is the best way to get what you want?" she asked. He looked down at the
ground knowing that she wouldn't like his answer. He hesitated, knowing that
the truth would only hurt. How was he going to tell her that the best way for
him to get what he wanted was to leave her?
18.
19.
To the two friends, the treehouse was much more than a treehouse. It was a
sanctuary away from the other kids where they could be themselves without
being teased or bullied. It was their secret fortress hidden high in the
branches of a huge oak that only they knew existed. At least that is what they
thought. They were more than a little annoyed when their two younger sisters
decided to turn the treehouse into a princess castle by painting the inside
pink and putting glitter everywhere.
20.





Area of a figure is a number (in square unit) associated with the part of the plane enclosed by
that figure.
Two congruent figures have equal areas but the converse is not true.
Area of a parallelogram = base X height 
Area of a triangle =
1
2
Area of a trapezium =
 base  height
1
2


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Key Notes


1
Area of rhombus = 
2

Parallelogram on the same base and between the same parallels are equal in area.

in area.


A parallelogram and a rectangle on the same base and between the same parallels are equal
Triangles on the same base and between the same parallels are equal in area.
If a triangle and parallelogram are on the same base and between the same parallels, then.
1
 Area of triangle 
2
A diagonal of parallelogram divides it into two triangles of equalareas.
In parallelogram ABCD, we have Area of ABD  area of ACD

The diagonals of a parallelogram divide it into four triangles of equal areas therefore
AOB)=ar( COD)=ar( AOD)=ar( BO
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Key Notes


If a parallelogram and a triangle are on the same base and between the same parallel, then
area of the triangle is equal to one half area of the parallelogram.
A median AD of a
ar( ABD)=ar( CD )


ABC divides it into two triangles of equal areas. Therefore
1
If the medians of a intersect at G, then ar( AGB)=ar( AGC )=ar( BGC )= ar 
3

Triangles with equal bases and equal areas have equal corresponding altitude.
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