Is y = x * cosx an even function and y = x * SiNx

Is y = x * cosx an even function and y = x * SiNx

Y = x * cosx is an odd function because f (- x) = - xcos (- x) = - x * cosx = - f (x)
Y = x * SiNx is even function because f (- x) = - xsin (- x) = x * cosx = f (x)
And their domain of definition is symmetric about the origin

In this paper, (SiNx + cosx / SiNx cosx) + sin2x + (cosx) 2 is reduced to the formula of TaNx

2(tanx)2/(tanx-1)
First, we rationalize the first denominator, then divide it all by (cosx) 2, and finally simplify it

The circumference of circle a is 12 cm, and that of circle B is 15 cm

Area ratio = (side length ratio) & 178; = (perimeter ratio) & 178; = 12 & 178;: 15 & 178; = 16:25
Hope to help you

As shown in the figure, the bottom is a rectangular pyramid p-abcd, and E is the midpoint of PC

Certification:
Connect AC, BD to o, OE
The quadrilateral ABCD is a rectangle
∴AO=OC
∵ e is the midpoint of PC
The OE is the median of △ ACP
∴OE//PA
∵ OE ∈ plane EBD
Ψ PA / / planar EBD

Given that the sector radius is 2000cm and the chord length is 243.7cm, how to calculate the arc length?

Center angle of sector circle = 2 * arcsin (243.7 / (2 * 2000)) = 2 * arcsin 0.061 = 7 degree
Arc length = 2 * 3.14 * 2000 * (7 / 360) = 244.22cm

Observe the equation 1x2 = 1 / 2 minus 1 / 2, 2x3 = 1 / 2 minus 1 / 3, 3x4 = 1 / 3 minus 1 / 4
What kind of rule do you find

N × n + 1 / 1 = 1 / n minus 1 / n

What are the good words and sentences from BaiCaoYuan to Sanwei bookstore?

1) Needless to say, the green vegetable beds, the smooth stone well fences, the tall acacia trees, the purple mulberries, the cicadas singing in the leaves, the fat wasps lying on the cauliflower, and the light call Skylark suddenly darting from the grass to the clouds. The short mud wall around the root area alone has infinite fun
2) The Chrysopidae is singing here, and the crickets are playing here. When they turn over the broken brick, they sometimes meet the centipede; and the cantharidin, if they hold its back with their fingers, will blow out a puff of smoke from the back orifice. The Caulis Polygoni Multiflori is entangled with the Caulis Manglietia, the Caulis Manglietia has lotus like fruit, and the Caulis Polygoni Multiflori has bloated roots

There is 30 M & sup 3; water in an open-air pool. After evaporation of XM & sup 3; (x ≤ 30) water, there is still YM & sup 3; water in the pool?
Draw two diagonals, a cm and B cm, to make the area 12m & sup3;, the function relationship between a and B?

(1)y=30-x (0≤x≤30)
(2)acm=a/100m,bcm=b/100m
s=1/2ab=12
ab=240000

Cut a cuboid 10 cm long, 8 cm wide and 12 cm high into two cuboids. What is the maximum sum of the surface area of the two cuboids
There must be a formula!

First, calculate the three side areas of the cuboid
They are 10x8 = 80, 10x12 = 120, 12x8 = 96
After cutting into two cuboids, the sum of the surface area is the original surface area plus twice the area of one side. Obviously, the sum of the surface area plus twice the area of the side with the area of 120 is the largest
So the maximum is: 2 * (120 + 96 + 80) + 240 = 832

sin(x－45°)＝-5/13,sin2x

Cos2 (x-45 °) = cos (2x-90 °) = - sin2x = 1-2sin (x-45 °) = 119 / 169
So SiNx = - 119 / 169