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3 years ago

Question 82 can u answer and tell me how this is the answer plzzz....

Mathematics

2 answers:

levacccp [35]3 years ago

7 0

The surface are would be 81 bc the base area is 9 and you have four triangles with the area of 18. Add them all up and you get 81

LiRa [457]3 years ago

4 0

It would be D, 81in2! I hope this helps, and you do well on your test! (:

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Solve the equation sin x + cos x=cos 2x for 0 27. x

vodka [1.7K]

Answer:

$x=\frac{\pi}{4}$ and $x=-\frac{3\pi}{4}$

Step-by-step explanation:

We are given that sin x+cos x=cos 2x

We have to solve the given equation for $0\leq x\leq 2\pi$

$sin x+cos x=cos^2x-sin^2x$

Because $cos 2x=cos^2-sin^2$

$sinx+cos x=(sinx +cos x)(sinx-cos x)$

$1 =sin x-cos x$

$sin x=cos x$

$\frac{sinx }{cos x}=1$

$tan x=1$

$tan x=\frac{sinx}{cos x}$

$tan x=tan\frac{\pi}{4}$

$x=\frac{\pi}{4}$

Tan x is positive in I and III quadrant

In III quadrant angle $\theta$ replace by $\theta -\pi$

Therefore, $tan x=tan (\frac{\pi}{4}-\pi)=tan\frac{\pi-4\pi}{4}=tan\frac{-3\pi}{4}$

$x=-\frac{3\pi}{4}$

8 0

3 years ago

Evaluate : limx→ tan2-sin2x x3

GrogVix [38]

Given:

$\lim _{x\to0}\frac{\tan 2x-\sin 2x}{x^3}$

Solve:

$\lim _{x\to0}\frac{\tan 2x-\sin 2x}{x^3}$

Use l'hopital's rule:

$\begin{gathered} =\lim _{x\to0}\frac{\frac{d}{dx}(-\sin 2x+\tan 2x)}{\frac{d}{dx}(x^3)} \\ =\lim _{x\to0}\frac{-2\cos (2x)+2\tan ^2(2x)+2}{3x^2} \end{gathered}$

Simplify:

$\begin{gathered} =\lim _{x\to0}\frac{-2\cos (2x)+2\tan ^2(2x)+2}{3x^2} \\ =\lim _{x\to0}\frac{2(-\cos (2x)+\tan ^2(2x)+1)}{3x^2} \end{gathered}$

Apply the constant multiple rule:

$\begin{gathered} \lim _{x\to0}cf(x)=c\lim _{x\to0}f(x) \\ \text{With c=}\frac{2}{3} \\ f(x)=\frac{-\cos (2x)+\tan ^2(2x)+1}{x^2} \end{gathered}$ $\begin{gathered} =\frac{2\lim _{x\to0}\frac{-\cos (2x)+\tan ^2(2x)+1}{x^2}}{3} \\ =\frac{2\lim _{x\rightarrow0}\frac{(4\tan ^2(2x)+4)\tan (2x)+2\sin (2x)}{2x}}{3} \end{gathered}$

Similary :

$\begin{gathered} =\frac{2\lim _{x\to0}(2\cos (2x)+12\tan ^4(2x)+16\tan ^2(2x)+4)}{3} \\ =\frac{2(6)}{3} \\ =4 \end{gathered}$

8 0

1 year ago

This beach ball has a surface area of 615.44 inches². What is its diameter? Use 3.14 for π.

aleksandr82 [10.1K]

Answer:

Step-by-step explanation:

6 0

3 years ago

Quadrilateral ABDE is a rectangle. DE = 4 in. and BD = 6 in. If the rectangle is rotated about a line through CF, cylinder Y is

postnew [5]

Answer:

1 in. is the answer.

Step-by-step explanation:

Solution: A Rectangle ABDE in which DE=4 inches and BD= 6 inches

There are two kinds of rotations

1. one along the Breadth, side having length 6 inches,i.e rotated along line GH, Cylinder Z is created.

Radius of cylinder Z=6/2= 3 inches

2. Second along the Length, Side having length 4 inches,i.e rotated about a line CF, cylinder Y is created.

Radius of cylinder Y= 4/2= 2 inches

Difference in Radii= Radius of cylinder Z - Radius of cylinder Y

= 3 - 2= 1 inches

Diagram shown below of both the cases:

7 0

3 years ago

Read 2 more answers

Please explain I'm really confused

castortr0y [4]

Sine is the opposite to the hypotenuse
so if sinA=0.6, suppose the opposite is 6, the hypotenuse is 10
now find the other leg by using a²+b²=c²: 6²+b²=10², b=8
sinB=8/10=0.8

8 0

3 years ago