You want to buy something that costs $98, and it's on sale for 30% off. What is the item's sale price?
First, convert the 30% to a real mathematical number. For percents, this is always done by dividing the 30% by 100%, or 30% / 100% = 0.300.
Second, find out what 30% of $98 is. This is the amount of the sale discount. This is always found by mulitplying 0.300 by the item's cost $98, like this:
0.300 x $98 = $29.40.
So for this sale, you'll save $29.40 on this item.
This means, the cost of the item to you is
$98 - $29.40 = $68.60.
I found the accompanying picture of this word problem.
The circle was inscribe in the triangle. The area outside of the circle but inside the triangle is the shaded area.
True. The shaded area of the following shape can be found by subtracting the area of the circle from the area of the triangle.
Where's the "triangle with alt. BD?" This problem can be solved without the diagram, but the solution would be easier with it.
BD is the altitude. Find the length of BD by finding the dist. between (-1,4) and (2,4); it is 2-(-1), or 3. |BD| = 3.
I've graphed the triangle myself and have found that the "base" of the triangle is the vertical line thru (2,1) and (2,6); its length is 6-1, or 5.
Thus, the area of this triangle is A = (b)(h) / 2, or A = (5)(3) / 2 = 10/3 square inches.
By Green's theorem, the integral of 
along 
is
which is 6 times the area of 
, the region with as its boundary.
We can compute the integral by converting to polar coordinates, or simply recalling the formula for a circular sector from geometry: Given a sector with central angle 
and radius 
, the area 
of the sector is proportional to the circle's overall area according to
so that the value of the integral is
