Answer:
150 square feet
Step-by-step explanation:
It is half of the yard, because it extends from the corners. To find the area of the triangle of grass, you have to find the product of the legs divided by two.
30*10=300
300/2=150
150 square feet of Mr. West's backyard is covered in grass
Let's work on the left side first. And remember that
the<u> tangent</u> is the same as <u>sin/cos</u>.
sin(a) cos(a) tan(a)
Substitute for the tangent:
[ sin(a) cos(a) ] [ sin(a)/cos(a) ]
Cancel the cos(a) from the top and bottom, and you're left with
[ sin(a) ] . . . . . [ sin(a) ] which is [ <u>sin²(a)</u> ] That's the <u>left side</u>.
Now, work on the right side:
[ 1 - cos(a) ] [ 1 + cos(a) ]
Multiply that all out, using FOIL:
[ 1 + cos(a) - cos(a) - cos²(a) ]
= [ <u>1 - cos²(a)</u> ] That's the <u>right side</u>.
Do you remember that for any angle, sin²(b) + cos²(b) = 1 ?
Subtract cos²(b) from each side, and you have sin²(b) = 1 - cos²(b) for any angle.
So, on the <u>right side</u>, you could write [ <u>sin²(a)</u> ] .
Now look back about 9 lines, and compare that to the result we got for the <u>left side</u> .
They look quite similar. In fact, they're identical. And so the identity is proven.
Whew !
Error// Error// Error// Error// Error// Error//
The correct answer is: -tan 32degrees
Consider a circle with radius 
centered at some point 
on the 
-axis. This circle has equation
Revolve the region bounded by this circle across the 
-axis to get a torus. Using the shell method, the volume of the resulting torus is
where 
.
So the volume is
Substitute
and the integral becomes
Notice that 
is an odd function, so the integral over ![\left[-\frac\pi2,\frac\pi2\right]](https://tex.z-dn.net/?f=%5Cleft%5B-%5Cfrac%5Cpi2%2C%5Cfrac%5Cpi2%5Cright%5D)
is 0. This leaves us with
Write
so the volume is
