On the application of cosine theorem and sine theorem In the triangle ABC, C = 90 °, BC = 3, AC = 4, P is the point on AB, find the maximum product of the distance from P to AC, BC

On the application of cosine theorem and sine theorem In the triangle ABC, C = 90 °, BC = 3, AC = 4, P is the point on AB, find the maximum product of the distance from P to AC, BC

Through P, PD is perpendicular to AC and D, through P, PE is perpendicular to BC and E, ab = 5,
Let AP = x, then BP = 5-x,
DP / AP = BC / AB = 3 / 5, so DP = 3x / 5. Similarly, PE = 4 (5-x) / 5, then PD * PE = 12x (5-x) / 25,
It's easy to find the maximum value of 12x (5-x) / 25. The maximum value is 3

How to write the past tense of "have" in the past tense of "dream" in the past tense of "play" in the past tense of "like"?

No had dreamed played liked

How to measure the resistance of a small light bulb? Please write down the experimental principle? The function of sliding rheostat?
According to the electric power

The principle of the experiment is volt ampere side resistance. The function of sliding rheostat is to change the resistance and voltage, and protect the circuit at the same time

In the experiment of RLC series resonant circuit, what are the advantages of using transistor millivoltmeter to measure voltage compared with common ammeter

The commonly used pointer voltmeter is a magnetoelectric measuring mechanism with rectifier circuit to measure AC voltage
The transistor millivoltmeter has larger internal resistance and wider frequency band than this kind of voltmeter

Marx: the basic principle of historical materialism
How does Marx expound the basic principles of historical materialism in the preface of critique of political economy?

"In the social production in which people live, there are certain and inevitable relations that do not depend on their will, that is, relations of production that are compatible with a certain stage of development of their material productive forces. The sum of these relations of production constitutes the economic structure of the society, The production mode of material life restricts the whole process of social life, political life and spiritual life, It is people's social existence that determines people's consciousness. When the social material productive forces develop to a certain stage, they will conflict with the existing production relations or property relations (which is just the legal term of production relations) in which they have been active. Then these relations will change from the development form of productive forces to the shackles of productive forces. At that time, the era of social revolution will come. "
main points:
1. Social existence determines social consciousness
2. The mode of production plays a decisive role in social life
3. Production relations must be suitable for the development of productive forces

How to read some words in English
English spelling and English standard of Michael and erataote

Michael ['maikl]
I think there may be some mistakes in the translation of allantot, because I have searched all over the dictionaries and there is no corresponding English translation, so I'm sorry
Good Luck!

If a = ccosb and B = ccosa, try to judge the shape of triangle ABC

I know it's a right triangle, but I haven't found a way to prove it

A = 2 * 3 * N2, B = 3 * N3 * 5, (n is prime), then the greatest common divisor of a and B is (), and the least common multiple is ()
A = 2 times 3 times the square of N, B = 3 times the cube of N times 5, (n is prime), then the greatest common divisor of a and B is? The least common multiple is?

A = 6N ^ 2, B = 15N, the greatest common divisor is 3N, the least common multiple is 30n ^ 2

In the isosceles triangle ABC, the center line on one waist AC divides the perimeter of the triangle into two parts: 15cm and 18cm, and calculates the length of each side of the triangle

1. Set the center line as BD
∴1/2AC+AB=15…… （1）
BC+1/2AC=18…… （2）
∴（2）-（1）：BC-AB=3
∵AB=AC
∴1/2AC+AC=15
AC=AB=10
∴BC=3+AB=13
2、1/2AC+AB=18
BC+1/2AC=15
AB-BC=3
∵AB=AC
∴AB+1/2AB=18
AB=AC=12
∴BC=AB-3=12-3=9
∴AB=AC=12
BC=9

The greatest common divisor of numbers 42 and 105 is______ The least common multiple is______ ．

42 = 2 × 3 × 7105 = 3 × 5 × 7, so the greatest common divisor of 42 and 105 is 3 × 7 = 21; the least common multiple is 2 × 3 × 5 × 7 = 210; so the answer is 21105