Two angles and the opposite sides of one of them correspond to the congruence of two equal triangles. Do the two angles refer to the two separate angles of two triangles This sentence is incomprehensible What is the equivalence of the opposite sides of a corner

Two angles and the opposite sides of one of them correspond to the congruence of two equal triangles. Do the two angles refer to the two separate angles of two triangles This sentence is incomprehensible What is the equivalence of the opposite sides of a corner

He means that the two angles of a triangle are known to be equal, and then the opposite sides of one of the two pairs are also equal

A cylinder, cut its height by 3cm, its surface area is reduced by 94.2cm2. How much is the volume of the cylinder reduced?
fast

What is the circumference of the base of the cylinder
94.2 △ 3 = 31.4cm
What is the base radius of the cylinder
31.4 ﹣ 3.14 ﹣ 2 = 5cm
What is the base area of the cylinder
5 × 5 × 3.14 = 78.5 square centimeter
The volume of the cylinder is reduced
78.5 × 3 = 235.5 cm3

How long does the earth live

How long is the life of the earth?
It is estimated that the earth has lived for 4.6 billion years. But how long can it live?
Scientists believe that if the earth is allowed to run freely, it may exist forever, but if other external factors interfere with it, the earth may die
In other words, all the energy and power on the earth come from the sun. Once the sun is short, it is bound to harm the earth. Before the 1930s, people always thought that the sun would burn out one day, turn from white to orange, then turn red, and finally turn into a silent dark star, In the 1930s, when physicists learned the mystery of the sun's glow and heat, the situation was very different. It turned out that the sun's energy came from its thermonuclear reaction, The life of the sun will go through the stages of gravitational contraction, main sequence star, red giant star and compact star. The main sequence star stage is the stable stage of the sun. This stage will last 10 billion years. At present, the sun only spends half of its time and is in its middle age. Once the sun reaches the stage of red giant star, the end of the earth will come. Of course, it will be billions of years later
Apart from the sun's interference with the earth, are there any other factors? Some scientists believe that the sun may have a brother, a companion star of the sun, which keeps circling the sun day and night. Every 26 million years, it will turn to the nearest place to the sun to "make waves and wind". Its strong gravity will cause great disturbance to many comets. One billion comets will collide in the solar system, The earth and other planets will become the "target" of these comets. If the mass of the comet colliding with the earth is large enough, the consequences will be unimaginable: the light ones will die out, and the ecology will change dramatically; the heavy ones will fall apart, and the earth will be "shattered". However, this sun companion that may bring accidents to the earth has not been found, but many scientists believe it exists
Which side of space will destroy the earth? When will the earth die?
(from the unsolved mysteries of the world)

1. To determine the specific heat capacity of lead in the future, heat 200 grams of lead to 98 ℃, and then put it into 80 grams of 12 ℃ water. After mixing, the water temperature is 18 ℃. If the heat loss is not included, the specific heat capacity of lead can be calculated?

The temperature of water is 12 to 18, and the specific heat capacity is 420,
So q = cm Δ t = 4200 x 0.08x (18-12) = 2016j (heat absorption)
So the lead exothermic 201.6j
Q=CMΔT 2016=CX0.2X（98-18）=126J/KG,C

If the height is shortened by 2 cm, the surface area will be reduced by 12 square cm
π take 3 fast

π is 3
Bottom perimeter: 12 △ 2 = 6 (CM)
Bottom radius: 6 △ 2 △ 3 = 1 (CM)
Because the perimeter of the bottom is equal to the height, the height is 6cm
Volume: 3 × 1 & # 178; × 6 = 18 (cm ^ 3)
Surface area: 1 & # 178; × 3 × 2 + 6 × 6 = 12 (cm ^ 2)

How much is 19 times 1 / 9
Urgent >_

19 times 1 / 9
It's equal to (18 + 1) times 1 / 9
It's 1 / 9 times 18 + 1 / 9 times 1
It's 2 + 1 / 9
It's two and one in nine

Given Tan α = 2, find Sin & sup2; α + sin α cos α - 2cos & sup2; α =?

tanα=2
sinα/cosα=2
sinα=2cosα
sin²α+sinαcosα-2cos²α
=(sinα+2cosα)(sinα-cosα)
=(2cosα+2cosα)(2cosα-cosα)
=4(cosα)^2
=4*(1+cos2α)/2
=2+2cos2α
=2+2[1-(tanα)^2]/[1+(tanα)^2]
=2+2[1-2^2]/[1+2^2]
=2-6/5
=4/5

As shown in the picture is a rectangular grassland, 16 meters long and 12 meters wide, with a road 2 meters wide in the middle. Calculate the area of grassland (shadow part)

The total length of the road is (16 + 12-2) meters, that is 26 meters. The area of the road is 26 × 2 = 52 (square meters), and the area of grassland is 16 × 12-52, = 192-52, = 140 (square meters). A: the area of grassland is 140 square meters

Simplify 2.4 to 5 / 8 and calculate the ratio

2.4:5/8=96/25

If the first term a ＞ 0, A2003 + a2004 ＞ 0, A2003 + a2004 ＜ 0, then the sum of the first n terms of the arithmetic case {an}
The largest natural number of Sn is: (1) 2002 (2) 2003 (3) 2004 (4) 2005

It should be A2003 + a2004 > 0, A2003 times a2004 < 0,
solution
A2003 × a20040, if the tolerance D ≥ 0, then each item of the sequence is constant and nonnegative, which is inconsistent with the known, so the tolerance d0 a20040 A1 > - 2002d
a1+2003d