What is the surface are of the cube below

Mathematics

2 answers:

AnnZ [28]4 years ago

4 0

the answer is simple and easy. why do you ask such question.

anyway answer is D i.e. 6l²(6*7*7)

alexdok [17]4 years ago

3 0

D is the answer

Hope this helped

You might be interested in

\int\limits^0_\pi {x*sin^{m} (x)} \, dx

Ket [755]

Let

$I(m) = \displaystyle \int_0^\pi x\sin^m(x)\,\mathrm dx$

Integrate by parts, taking

u = x ==> du = dx

dv = sinᵐ (x) dx ==> v = ∫ sinᵐ (x) dx

so that

$I(m) = \displaystyle uv\bigg|_{x=0}^{x=\pi} - \int_0^\pi v\,\mathrm du = -\int_0^\pi \sin^m(x)\,\mathrm dx$

There is a well-known power reduction formula for this integral. If you want to derive it for yourself, consider the cases where m is even or where m is odd.

If m is even, then m = 2k for some integer k, and we have

$\sin^m(x) = \sin^{2k}(x) = \left(\sin^2(x)\right)^k = \left(\dfrac{1-\cos(2x)}2\right)^k$

Expand the binomial, then use the half-angle identity

$\cos^2(x)=\dfrac{1+\cos(2x)}2$

as needed. The resulting integral can get messy for large m (or k).

If m is odd, then m = 2k + 1 for some integer k, and so

$\sin^m(x) = \sin(x)\sin^{2k}(x) = \sin(x)\left(\sin^2(x)\right)^k = \sin(x)\left(1-\cos^2(x)\right)^k$

and then substitute u = cos(x) and du = -sin(x) dx, so that

$I(2k+1) = \displaystyle -\int_0^\pi\sin(x)\left(1-\cos^2(x)\right)^k = \int_1^{-1}(1-u^2)^k\,\mathrm du = -\int_{-1}^1(1-u^2)^k\,\mathrm du$

Expand the binomial, and so on.

8 0

3 years ago

Wey wey drops a pencil in her cup and notices that it only fits diagonally. the pencil is 9 centimeters long and the cup is 7 ce

vesna_86 [32]

Answer:

5.656854249 cm

Step-by-step explanation:

Use the Pythagorean theorem to solve this (assuming that the bottom of the cup is a right angle). $a^{2} +b^{2} =c^{2}$ . a and b are sides, and c is the hypotenuse.

The length of the pencil would be the hypotenuse (c), and how tall the cup is (7 cm) would be one of the sides (a). The diameter of the cup, would be the other side (b).

Plug this into the Pythagorean theorem to get the equation: $7^{2} +b^{2} =9^{2}$ . From here, we can find the diameter of the cup by isolating b - remove everything from the left side, but remember, what you do to one side you must do to the other.