If the length of an arc is equal to one-third of the radius, the angle of the center of the arc is

2nπr/360°＝r/3
n＝60°/π≈19.11°

As shown in the figure, ab ‖ CD, ∠ 1 = 50 ° and ∠ 2 = 110 °, then ∠ 3=______ Degree

∵∠2=110°，
∴∠4=70°，
∵AB∥CD，
∴∠5=∠1=50°，
Using the interior angle sum theorem of triangles,
It can be found that ∠ 3 = 180 ° - ∠ 4 - ∠ 5 = 60 °

As shown in the figure, ab ‖ CD, AF intersect CD at e, ∠ CEF = 140 °, then ∠ a=______ °．

∵∠CEF=140°，
∴∠CEA=180°-∠CEF=40°，
∵AB∥CD，
Ψ a = ∠ CEA = 40 ° (the two lines are parallel and the internal staggered angle is equal)
So the answer is: 40

The time zone of 105 ° e central meridian

15 degrees is a time zone. The best way to find the time zone from longitude is to divide the given longitude by 15 degrees, and then round to one decimal place
105 degrees divided by 15 degrees is exactly 7, so it's the seventh East District

What is the time zone of the 105 degree e central meridian?

The east zone is 105 degrees east
The east longitude is the eastern time zone, 105 / 15 = 7, so it is the seventh east area

What is the time zone of the 100 ° e meridian_ The central meridian of the time zone is_ E.

General method: divide the required longitude by 15. For example, if the time zone of 75E is 75 / 15 = 5, then it is in the east 5 area, and the central meridian is 75E. If it can not be divisible, look at the remainder. If the remainder is less than 7.5, then add one to the division result. Example 1: find the time zone where 115e is located. First use 115 / 15 = 7, and the remainder is 5, Therefore: 100 / 15 = 6 more than 10, so 100e is in the East 7 area, and the central longitude is 7 * 15 = 105E

The meridians forming a coil with 30 ° w meridian are () a, 110 ° EB, 120 ° WC, 150 ° WD, 150 ° E

D. From 0 degrees, let the west be negative, so 30 W is - 30 degrees; the opposite should be - 30 + 180 = + 150 degrees

Is the central meridian the same as the central meridian? I don't know if the central meridian refers to the central longitude of each belt. The central meridian we have been using is 114. What is the basis for this? Is the central meridian used all over the country 114?

All meridians are also called meridians. The central meridians are the meridians in the middle of each time zone. The regional degree is the number of time zones in the time zone multiplied by 15 degrees. For example, the central longitude of the eighth east district is 8 × 15 degrees = 120 ° E

Set point o as a point in the triangle ABC, connecting OA, ob, OC, known angle AOB = 105 degrees, angle BOC = 125 degrees Try to explain that the angles of the triangle formed by the lines OA, OB and OC are 65 degrees, 55 degrees and 60 degrees respectively (questions related to rotation) It's an equilateral triangle. Angle AOB = 115, angle BOC = 125

It's changed
Let OA = a, OB = B, 0C = C
As shown in the figure:
Rotate the triangle AOB 60 degrees to ACD, then:
OA = AD = a
OB = CD = b
Connect OD, then:
Angle oad = angle OAC + angle CAD = angle OAC + angle Bao = 60 degrees
Therefore, the triangle oad is an equilateral triangle
So: od = a
In the triangle OCD, the lengths of the three sides are a, B and C respectively
Angle doc = angle AOC - angle AOD = (360 - 115 - 125) - 60 = 60
Angle ODC = angle ADC - angle ADO = angle AOB - angle ADO = 115 - 60 = 55
Angle OCD = 180 - 60 - 55 = 65

There is a point O in the equilateral triangle ABC, and OA = 10, OB = 6, OC = 8. Find the degree of ∠ BOC

Rotate △ BOC around C so that BC and AC coincide, O falls at o 'to obtain △ ACO', and connect oo`
Then OC = OC '∠ OCO' = 60 °
∴OO`=6 ∠OO`C=60°
In △ aoo ', OO' = 6 Ao = 10 Ao '= 8
∴∠AO`O=90°
∴∠AO`C=90°+60°=150°
∴∠B0C=150°

If the length of an arc is equal to one-third of the radius, the angle of the center of the arc is