How to solve this math problem

There are 5 Saturdays in February, which means that it is 29 days, and February 29 is a Saturday, which is a leap year, because there will be a maximum of 4 Saturdays in a normal year (4 times 7 equals 28).

Then, March 1 is Sunday, and the number of days from March to December is calculated

31 days per month 30 days per month.

A total of 6 31 4 30 306

306 7 43 surplus 5

Based on the above deduction that March 1 is a Sunday and the number of days remaining is 5, it can be concluded that January 1 of the next year's New Year's Day is a Friday.

The key point is that according to the 5 Saturdays out is a leap year, February 29 is a Saturday.

The square of a cos + the square of b sin.

The square of a (the square of the sin + the square of the cos) the square of the cos + the square of b (the square of the sin + the square of the cos) the square of the sin.

The square of a + the square of b + the square of a * tan + the square of b * the square of cot.

The square of a + the square of b + the square of a * the square of tan + the square of b - the square of b * the square of cot.

The square of a + the square of 2*b + the square of a * tan - the square of b * the square of cot.

The square of a + the square of 2*b + (the square of a - the square of b) * the square of cot.

Because a>b>0

So: the square of a - the square of b 0

When the minimum value is the square of cot = 0, i.e., the square of a + the square of 2*b.

Original Lu Shijing = 1 2-1 Early Caution 3 + 1 3-1 4 + ......1 Talk 9-1 10

Calculate the answer] rotten Zen eof=115°

Problem Solving Idea] Since AOB is a flat angle, i.e. AOB=180°. So AOC + COD + BOD=180°

And since OE is the angular bisector of AOC and of of is the angular bisector of BOD, then there is AOC=2X1 and BOD=2X2

Solution: Suppose aoe=x1, dof=x2. Since OE is the angular bisector of AOC and of of is the angular bisector of BOD, then there is.

aoc=2x1，∠bod=2x2

The dust from hunger to AOB is a flat angle, i.e. AOB=180°. So.

aoc + cod +∠bod=2x1+50°+2x2=180°

To simplify the above, there is.

x1+x2=65°

So, eof=x1+50+x2=50+65=115°

Knowledge points of this question].

1. Flat angle. A ray rotates around its endpoint, and when the beginning and end edges are in the same straight line and in opposite directions, the resulting angle is called a flat angle.

Straight angle. 2. Angular bisector. A ray (line within the corner) is drawn from the vertex of an angle and the angle is divided into two identical angles, which is called the angular bisector of the angle.

Angular bisector. Angular bisector nature:

1.The three angular bisectors of the triangle intersect at one point and are at equal distances to each side. This point is called the inner circle (i.e. an inscribed circle can be drawn inside the triangle with this point as the center of the scattered circle).

2.The two segments obtained by bisector lines at the inner corners of a triangle are proportional to the two sides of the corner.

3. The difference between flat angles and straight lines

1) A flat angle is an angle, which meets the definition of angle; A straight line is a "line";

2) The flat angle can be measured, 1 flat angle = 180 degrees; Straight lines are not measurable;

3) The most obvious difference is that a flat angle has a vertex and two edges, while a straight line does not.

ab 丨 ab丨 Zheng Hao 1, that is, 丨 ab丨 ab, ab with the same name (with the positive town Cong fiber negative), when a, b is a positive number, the original formula 1+1+1 3, when a, b is a negative number, the original formula -1-1+1 -1, the selected original formula -1 or 3, choose d

Assuming that there is no table of contents, preamble, etc., the page number starts with 1.

The page number is 1-9 with one digit, a total of 1 9 = 9 digits.

Pages numbered 10-99 with two digits totaling 2 90 = 180 digits.

The remaining number is 201-180-9 = 12.

Note that 12 3 = 4

So there are only four pages with a three-digit page number.

So this book has103 pages<> girders fiber.

Solution: a b, <1=50 degrees, 50 degrees and 28 degrees.

22 degrees.

2(x-1) a - x/3 > 1

Next, we try to equalize the solution ranges of the two inequalities, i.e., make their solutions the same. We multiply the first inequality by the reciprocal of the division by 2) and multiply the second inequality by 2 (i.e. divide by 1 2) to get:

3(x-1) <3

2a - x > volts 2

Now we can see that the intersection of the solutions of these two inequalities is:

5 > x

Since we want to ensure that the solutions of the inequalities are equal, both of the above inequalities must be true. Multiplying the second closed inequality by -1 and noting that the coefficient of x is -1, we get:

5 < x

Substituting this inequality into the first inequality gives :

3(x-1) <3 < 3(x-1) +152x - 1 < 2x + 7

Divide both sides at the same time to get:

4 3) x - 2 3) Negative infinity < a < positive infinity.

So a can take any real number.

2 (x-1) Sakura reeds 1

3a-x>3

x<3a-3

Inequality 2 (envy x 1)1 has the same range of solutions.

Let a 2+2 = 3a-3

5=3a-a/2

5=5a/2

a=2a has a value of 2