Now one of the first things we are going to focus on, is to labeling identifying so we
can recognize which shape is which. I am going to label the top one across here as area 1,
let me just do that now – there is our area 1 and down below here we will call it area
2 – ok we identify and mark out each composite area.
Now our task is to work out each individual area let us start of area 1 – so with area
1 – that is going to be half of a circle, which is half x the area of a circle, now
the area of a circle is pi R squared, now because it is a semi-circle half of a circle,
now it is going to be half – x pi R squared. Now interestingly enough we have not been
given the radius, have we? We have the length across here which is 18 m which is the same
if we go above here which is essentially the diameter of the circle because from one into
the circle of the circle all the way across to the other into the circle so looking at
finding what the radius is. Well if the diameter across here is 18m which is the same up here
then the radius is half of that which is clearly means it is 9m so R is 9m. so that is the
radius let us plunk the values into the area 1 – that is pi R squared so there would
be square up there. So point that in the calculator so ½ times pi times 9 squared equals – Area
one in total all of it right across is 127.23 meters squared because it is an area. So all
that up above Area one 127.23 meter squared so only mark that and highlight that – these
are area one. Now let’s go for Area two.
Now area two down below here, here’s a one strip of a rectangle so that’s pretty basic
in term of rectangle areas, it’s going to be length times breadth, yeah? so that equals
length times breath of width which ever you prefer and that equal length across area 18
times breadth, the height there the breath 4 meters so the total for Area two equals
18 times 4 which is a grand total of 72 meters squared. These are our both areas, all we
need to do is add up both areas together – it’s going to be – Area one plus area two what
is that going to give us? So that’s 127.23 meter squared plus 72 meter squared – let’s
add up together on the calculator 127.23 plus 72 all together, grand total, whole area of
the composite is – 199.23 meter squared.
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