10.1 Geo

10.1 Area of Circles, Parallelograms, Triangles

Poll

Is area the section inside a shape or the outside of a shape?

• Inside

• Outside

Area of Circle

•  *** $A=\pi r^2$  ; What does 'r' represent?

• Radius

• If the r=6, what is the diameter?

• If the diameter is 3, what is the r=?

• If the r=5, what is the radius?

Fill in the Blanks

What would be the area of this circle? Round the nearest tenth

Notice how the height is not the slanted sides - it's truly how tall the parallelogram is. The area formula for a parallelogram is just A=bh

Multiple Choice

What is the area of this parallelogram?

• $120\ in^2$

• $120\ in$

• $23$

• $120in^3$

Area for Triangle

• How do you think the areas for a square (bh) and a triangle are going to be similar?

•  $A=\frac{b\cdot h}{2}$  ***

Multiple Choice

Find the area of the triangle

• $544in^2$

• $272in$

• $272in^2$

Fill in the Blanks

Find the area of the shape made up of a square and a right triangle - do not include units

#11 from HW

Can we split this into two different shapes that we know the area formulas for? (Rectangle and triangle?)

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What was the area for the previous shape? *You don't need the unit, just the number*

Painting a room

With the people around you, calculate what the area of wall you would have to paint total. (Take it wall by wall and don't forget the ceiling and to exclude the windows/door!)

Fill in the Blanks

What is the area of that room? (Round to 2 decimal places, and don't include the unit)

Fill in the Blanks

One gallon of paint covers

 $65.74\ in^2$  . How many gallons do you need for this room? (Round up to the nearest gallon)

Fill in the Blanks

At $16.34/gallon, how much will you spend on paint?