Geometry is too bad to understand the formula, please master to calculate, chord length 6 meters, chord center to arc top 1.7 meters, find an arc length, thank you

Geometry is too bad to understand the formula, please master to calculate, chord length 6 meters, chord center to arc top 1.7 meters, find an arc length, thank you

Chord length L = 6m, chord center to arc top H = 1.7m, find an arc length C? The radius of arc is r, the center angle of arc is A.R ^ 2 = (R-H) ^ 2 + (L / 2) ^ 2R ^ 2 = R ^ 2-2 * r * H + H ^ 2 + L ^ 2 / 42 * r * H = H ^ 2 + L ^ 2 / 4R = H / 2 + L ^ 2 / (8 * h) = 1.7 / 2 + 6 ^ 2 / (8 * 1.7) = 3.497m, a = 2 * arc sin ((L / 2) / R) = 2 * arc sin ((...)

What is 135 ° equal to?

-1

Help me to simplify and calculate the following questions
1. Simplification: 15 out of 25 = few, 27 out of 69 = few, 22 out of 95 = few, 4 out of 51 = few, 40 out of 104 = few, 68 out of 132 = few, 35 out of 45 = few, 21 out of 63 = few, 48 out of 56 = few. 2. Calculation: 1-1 out of 3-2, 1 out of 8 = 7 out of 9 + 5 out of 7 = 5 out of 8 + 1 out of 6 = 1 out of 3-2, 1 out of 8 = 1 out of 10 + 3 out of 4 = 1 out of 2-3 + 3 out of 4 = 3 out of 5 + 1 out of 2 = few,

The results are as follows: 1. Simplification: 15 out of 25 = 3 out of 5, 27 out of 69 = 9 out of 23, 22 out of 95 = 22 out of 95. It has been simplified by 4 out of 51 = 4 out of 51, 40 out of 104 = 5 out of 13, 68 out of 32 = 17 out of 33, 35 out of 45 = 7 out of 9, 21 out of 63 = 1 out of 3, 48 out of 56 = 6 out of 7

Calculation and simplification
1. (1 / 2 √ 28-3 / 2 √ 84) × √ 14 2
3.3√48-9√1/3+3√12 4.（√48+√20）+（√12-√5）
5.√2×√6/√3-1 6.√（√3+1）（√3-1）
7. √ 72-4 √ 1 / 2-1 / 7 √ 98 + √ one after another 1 / 8 8. √ 9A + A / 3 √ 1 / A + 1 / 2A √ a ^ 3
9.(2+√3^2008)(2-√3)^2006 10.（√3a-3√27a^3)÷√a/3

1.(1/2√28-3/2√84)×√14
=(√7-3√21)×√14
=√7(1-3√3)×√7×√2
= 7√2(1-3√3)
=7√2-21√6
2. √ one and three parts △ two and three parts × √ one and five parts
=√(4/3)÷√(8/3)×√(8/5)
=√(4/3)÷[√(4/3)×√2]×√(8/5)
=1÷√2×√(8/5)
=√2/2×2√(2/5)
=√2×√(2/5)
=√2×√10/5
=√20/5
=2√5/5
3.3√48-9√1/3+3√12
=12√3-3√3+6√3
=15√3
4.（√48+√20）+（√12-√5）
=4√3+2√5+2√3-√5
=6√3+√5
5.√2×√6/(√3-1)
=2√3/(√3-1)
=2√3(√3+1)/[(√3-1)(√3+1)
=2√3(√3+1)/2
=√3(√3+1)
=3+√3
6.√（√3+1）（√3-1）
=3-1
=2
7. √ 72-4 √ 1 / 2-1 / 7 √ 98 + √ one after another 1 / 8
=6√2-2√2-√2+√(9/8)
=3√2+3√(1/2)/2
=3√2+3√2/4
=15√2/4
8.√9a+a/3√1/a+1/2a√a^3
=3√a+√a/3+√a/2
=18√a/6+2√a/6+3√a/6
=23√a/6
9.(2+√3)^2008(2-√3)^2006
=(2+√3)^2*(2+√3)^2006*(2-√3)^2006
=(2+√3)^2*[(2+√3)(2-√3)]^2006
=(2+√3)^2*1^2006
=(2+√3)^2
=7+4√3
10.（√3a-3√27a^3)÷√(a/3)
=（√3a-9a√3a)÷√(a/3)
=√3a(1-9a)÷√(3a)/3
=(1-9a)÷1/3
= (1-9a)*3
=3-27a

Simplification before calculation
（x+y)^2-4(x+y)(x-y)+3(x-y)^2
The values of x = 5 and y = - 4 / 5 are obtained

=((x+y)-(x-y))*((x+y)-3(x-y))
=2y*(4y-2x)
=4y*(2y-x)
Carry in = 4 * - 0.8 * (- 1.6-5) = 4 * 0.8 * 6.6 = 21.12

Who can simplify before calculating
{1 / (A-2) + (A & sup2; - 1) / (A & sup2; - A-2)} / {A / (A-2)} & sup2; = when a = 3, the original formula = how much

When a = 3, the original formula is 1 / 3
..

Mathematical simplification before calculation=+
Square of (2x + y) + 4 (x + 2Y) (2y-x) - 4Y (x + 2Y) where x = 2006, y = - 1

(2x+y)^2+4(x+2y)(2y-x)-4y(x+2y)
=4x^2+4xy+y^2-4x^2+16y^2-4xy-8y^2
=9y^2
Take x = 2006, y = - 1 into the original formula
Original formula = 9 * (- 1) ^ 2 = 9

The first step is to simplify the calculation
3.25*13.7*4.4
The detailed process must be calculated simply

3.25*13.7*4.4
=(3.25*4)*(13.7*1.1)
=13*15.07
=13*15+13*0.07
=195+0.91
=195.91

-p^2 cos180°+q^2 sin90°-2pq cos0°=?

(P-Q) square you see, you do not say to give some money, very difficult to answer a question

Simplify - α & sup2; cos180 ° + β & sup2; sin90 ° - 2 α β cos0 °

－α²cos180°+β²sin90°－2αβcos0°
=－α²×（-1）+β²×1－2αβ×1
=α²+β²－2αβ
=（α-β）²