As shown in the figure, ab = AC, ∠ BAC = 120 ° in △ ABC, ad ⊥ AC intersects BC at point D, and BC = 3aD

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• 1. As shown in the figure, ab = AC, ∠ BAC = 120 ° in △ ABC, ad ⊥ AC intersects BC at point D, and BC = 3aD
• 2. As shown in the figure, ab = AC, ∠ BAC = 120 ° in △ ABC, ad ⊥ AC intersects BC at point D, and BC = 3aD
• 3. As shown in the figure, ab = AC, ∠ BAC = 120 ° in △ ABC, ad ⊥ AC intersects BC at point D, and BC = 3aD
• 4. As shown in the figure, ab = AC, ∠ BAC = 120 ° in △ ABC, ad ⊥ AC intersects BC at point D, and BC = 3aD
• 5. It is known that AC = 6BC = 8 in RT △ ABC, and Tan ∠ CDE can be obtained by turning an acute angle of it It is known that in RT △ ABC, ∠ C = 90 °, AC = 6, BC = 8, fold an acute angle so that the vertex of the acute angle falls at the midpoint D of the opposite side, and the crease intersects the other right edge at e and the oblique edge at F. the value of Tan ∠ CDE is obtained
• 6. The negative number represented by 5 unit length points on the number axis and the origin is (), and its distance from the point representing 2 is ()
• 7. 220 V power supply with 380 V motor 220 V household power supply with 380 power electric motor, do not turn on the buzzing sound, for a while the motor is hot, what are the consequences? What is the solution? Say! The key is that it turns today. It turns normally! Guys don't often play a little temper!
• 8. In a series circuit, the greater the total resistance, the less the total power of the circuit? A DC motor, with rated voltage of 220 V, normal working resistance of 40 ohm and electric power of 60 kW, what is its normal working current? In the series circuit, it is known that the power supply voltage is 4.5 V, the range of the voltmeter is 0-3 V, the maximum resistance of the sliding rheostat R is 10 ohm, and the small bulb L is marked with the word "2.5V 1.25W". After closing the switch, when the small bulb lights normally, what is its resistance? What is the resistance of the sliding rheostat connected to the circuit / if the resistance of the small bulb remains unchanged, in this circuit, What is the minimum power of a small light bulb? In a series circuit, if the total resistance in the circuit is three times of the original by moving the slide P, how much heat is generated in the same time?
• 9. It is known that the rated power of electric iron is 70W, and the voltage is 220V, I and R are calculated
• 10. What is the allowable working current of 2K ohm resistor with rated power of one eighth watt at 12V
• 11. As shown in the figure, in the acute angle △ ABC, ab = 4, BC = 5, ∠ ACB = 45 °, rotate △ ABC counterclockwise around point B to obtain △ a1bc1. (1) as shown in Figure 1, when point C1 is on the extension line of line Ca, calculate the degree of ∠ cc1a1; (2) as shown in Figure 2, connect Aa1 and CC1. If the area of △ aba1 is 4, calculate the area of △ cbc1
• 12. As shown in the figure, rotate the right angle triangle ABC (where ∠ ABC = 60 °) clockwise around point B to the position of a1bc1, so that points a, B and C1 are on the same straight line. If the length of AB is 10, then the distance from point a to point A1 is equal to the distance______ (results π reserved)
• 13. As shown in the figure, ab = BC, ∠ ABC = 90 ° in △ ABC, and △ ABC rotates clockwise around point B to △ a1bc1, and the rotation angle is α, 0 °
• 14. In △ ABC, ab = BC, ∠ a = ∠ C = 45 ° rotate △ ABC clockwise around point B by an angle α (0 ＜ α ＜ 90 °) and △ MBN, BM intersect AC with point E, Mn intersect AC, BC with D and f respectively (1) When α =? EM is the longest; (2) Observe and guess the quantitative relationship between EM and FC in the process of rotation, and explain the reason There should be an answer before 6:30 tomorrow, otherwise it will be invalid
• 15. As shown in the figure, in RT △ ABC, ∠ ACB = 90 °, point D is a point on the hypotenuse AB, make ∠ CDE = ∠ a, pass through point C, make CE ⊥ CD, cross De to e, connect be Verification: ab ⊥ be
• 16. In RT △ ABC, CD is the bisector of BCE. BCE = 60 °∠ 3 = ∠ 4. Describe the relationship between CB and CE. What's your conjecture? And prove it Note that it's in the RT triangle
• 17. In RT △ ABC, ∠ C is equal to 90 degree CD.CE If ∠ A is equal to 30 °, try to judge the shape of ∠ BCE Geometric steps, is an equilateral triangle
• 18. As shown in the figure, in the triangle ABC, the angle BAC = 90 ° and BD is the bisector of the angle ABC. The extension line of BD is perpendicular to the line passing through point C and E, and the extension line of CE intersecting Ba is F. the proof is: BD = 2ce Please help me
• 19. As shown in the figure, in the triangle ABC, ab = BC, ad is the middle line on BC, extend BC to point E, make CE = BC, prove: AE = 2ad
• 20. As shown in the figure, ad is the middle line of △ ABC, point E is on the extension line of BC, CE = AB, ∠ BAC = ∠ BCA, verification: AE = 2ad