In the triangle ABC, a, B and C are the three sides corresponding to angles a, B and C. We know that B * B + C * C-A * a = BC. (1) find the value of angle A

In the triangle ABC, a, B and C are the three sides corresponding to angles a, B and C. We know that B * B + C * C-A * a = BC. (1) find the value of angle A

Cosine theorem, yes
cosA=b²+c²-a² / 2bc =1/2
A=π/3

The meaning of multiplication in second grade mathematics

Represents the addition of several identical numbers
For example, the sum of four five is 20, which is expressed as 4 × 5 = 20
Similarly, 20 can also be divided into 4 5, which is division operation
So multiplication and division are interchangeable

Column formula with fractional multiplication calculation!
Zhang Qiang watched a science and education film on the Internet. When it was played to 1 / 3, he answered a phone call. At the end of the call, he found that the remaining part that was not played was 4 / 5 of what he played when he went to answer the phone. When Zhang Qiang came back from the phone call, how many parts were still not played?
Come on,

1-4/5=1/5
1/3-1/5=2/15
1/3+2/15=7/15
1-7/15=8/15
Sorry, it's wrong

A kind of multiplication operation is explored
36×34=100×3×（3+1)+6×4 =1224
62×68=100×6×（6+1）+2×8=4216
83×87=100×8×（8+1）+3×7=7221
……
(1) Can you use what you have learned to explain the mystery?
(2) Using the law you found, find the value of 35 & # 178; and 496 × 494

(1)、（10a+b）×[10a+（10-b）]=10a×10a+10a(10-b)+10ab+b(10-b)=10a(10a+10-b+b)+b(10-b)=100a(a+1)+b(10-b)
（2）、35×35=100×3×（3+1）+5×5=1200+25=1225
496×494=100×49×（49+1）+6×4=245000+24=245024

What is the meaning of mathematical e?

"E is the base of natural logarithm." "natural logarithm is a logarithm function with E as the base. E is an irrational number, which is about 2.718281828. The symbol e represents a natural constant in mathematics and a numerical value like π. They are all irrational numbers. The formula of E = 1 + 1 / (1!) + 1 / (2!) + 1 / (3!) + 1 / (4!) +... + 1 /

The mathematical meaning of e
e^3

LIM (n + 1 / N) n power = e

What does e ^ k mean in mathematics

E is the base and ^ k is the power of K
For example: 2 ^ 3 represents the cubic power of 2. It is 2x2x2 = 8

What's the meaning of math e
Such as the title

It is mainly used in natural logarithm as the base of logarithm
Y = LNX and y = 1 / X
In this way, everything related to the inverse proportional function will have a natural logarithm after integration

Why invent mathematics

Ha ha, in order to let you know how old you are this year, in order to let you know how much it costs to buy an ice cream, mathematics can calculate the visible things... But not the things you think

Is our mathematics (I am a senior three) discovered or invented?
Who knows?

Yang Fan knows that happiness is symbolized by facts, scientists invent, and mathematicians think that mathematical abstraction is made