Answer:
789 m²
Step-by-step explanation:
Consider the cross section created by a vertical plane through the apex of the pyramid and bisecting opposite sides. The cross section is an isosceles triangle with base 20 m and height 17 m. One side of this triangle is the slant height of the face of the pyramid.
The side of the triangle above can be found using the Pythagorean theorem. A median from the apex of the triangle will divide it into two right triangles, each with a base of 10 m and a height of 17 m. Then the hypotenuse is ...
s² = (10 m)² +(17 m)² = 389 m²
s = √389 m ≈ 19.723 m . . . . . slant height of one triangular face
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The area of one triangular face is ...
A = (1/2)sb
where s is the slant height above, and b is the 20 m base of the face of the pyramid. There are 4 of these faces, so the total area is ...
total lateral area = 4A = 4(1/2)sb = 2sb = 2(19.723 m)(20 m)
total lateral area ≈ 789 m²
Answer:
20 degrees
Step-by-step explanation:
Factor 25 out of 25a^2−100.
Factor 25 out of 25a^2.
25(a^2)−100
Factor 25 out of −100.
25a^2+25⋅−4
Factor 25 out of 25a^2+25⋅−4.
25(a^2−4)
Rewrite 4 as 2^2.
25(a^2−2^2)
Factor.
Since both terms are perfect squares, factor using the difference of squares formula, a^2−b^2=(a+b)(a−b) where a=a and b=2.
25((a+2)(a−2))
Remove unnecessary parentheses.
25(a+2)(a−2)
I believe this is correct.
A cube, is made off 6 squarial faces, so all faces on that cube, are squares, the front, back, left, right, top and bottom.
a square has all equal sides, and also all right angles, so all angles in a square are 90°. Let's say the sides are "x" long.
now, if we run a plane on that cube diagonally, check the picture below, the diagonal side at the bottom, by usin the 45-45-90 rule as you see it there, will be x√2.
let's keep in mind that, "x" is opposite side of that angle θ, and then x√2 will be the adjacent side of it.
and we can use those two to get the tangent and then the inverse tangent to get the value, as you see it in the picture.
if you need the angle in radians, run the inverse tangent again, just make sure your calculator is in radians mode.