Answer:
Step-by-step explanation:
sin(90-a)=cos
cos = angle adjacent
theta=BC/CA
To find the lateral surface area of a pyramid, you can find the area of each triangle, A = 1/2bh or A = 1/2lw, then multiply by the number of triangles, which would be based on the number of sides of the base; or you can take half the perimeter and multiply by the slant height.
20 should be the answer because 205 divided by 10 =20
(sorry if it's too late and you've already figured it out, but here you go anyway)
The easiest way to do this is to start by FOILing then add.
So just start with (x-1)(x-1)
(x-1)(x-1)
Front: (x*x) = x^2
Outer: (x*-1) = -x
inner: (-1*x) = -x
Last: (-1*-1) = 1
Added: x^2 -2x +1
Now take that answer and do the same thing with (x-1). It's basically the same thing, just with an added thing you need to multiply.
(x-1)(x^2-2x+1)
(x*x^2) = x^3
(x*2x) = 2x^2
(x*1) = x
(-1*x^2) = -x^2
(-1*-2x) = 2x
(-1*1) = -1
Now add everything together:
x^3+2x^2+x-x^2+2x-1
The answer is:
x^3+x^2+3x-1
