It is known that AB is parallel to EF, CD, ad is parallel to BC, and BD is bisected
The quadrilateral ABCD is a parallelogram, Δ ADB ≌ Δ CBD, and is an isosceles triangle
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- 1. In △ ABC, the angle ABC = 90, ad is the angular bisector, the points E F are on AC ad, and AE = AB EF / / BC prove that bdef is a diamond
- 2. As shown in the figure, it is known that P is a point on the side BC of △ ABC, and PC = 2PB. If ∠ ABC = 45 ° and ∠ APC = 60 °, find the size of ∠ ACB
- 3. P is any point in the equilateral triangle ABC, PA = 3, Pb = 5, PC = 4, find the angle APC
- 4. Equilateral triangle ABC, P is a point in the triangle, PA is equal to 3, Pb is equal to 5, PC is equal to 4, find the degree of ∠ APC
- 5. In RT △ ABC, ∠ ACB = 90 °, ∠ BAC = 30 °, BC = 1, P is a point in △ ABC, and ∠ APC = ∠ BPC = ∠ APB = 120, calculate the value of PA + Pb + PC
- 6. In the tetrahedral PABC, PA = Pb = PC = 2, APB = BPC = APC = 30 degree In the tetrahedral PABC (P is the vertex), PA = Pb = PC = 2, ∠ APB = ∠ BPC = ∠ APC = 30 °, starting from point a, circling along the tetrahedral surface, and then returning to point a, the shortest distance is
- 7. In the triangle ABC, the area of BDE, DCE and ACD are 90, 30 and 28 square centimeters respectively?
- 8. Given that the points D and E are on the sides AB and AC of △ ABC, de / / BC, the area of △ ABC is s, BC = a, and the area of △ ade is S1, the length of De can be obtained (expressed in the algebraic form of the letters s, S1 and a) A D E B C
- 9. Given that points D and E are on edges AB and AC of △ ABC, de / / BC, the area of △ ABC is s, BC = a, and the area of △ ade is S1, the length of De can be obtained It is represented by the algebraic expression of the letters s, S1 and a
- 10. In the acute triangle ABC, be is perpendicular to AC, D is the upper point of AB, angle ade = angle c, s triangle ade area is S1, and △ ABC area is S2, then S1 / S2 is
- 11. As shown in the figure, in △ ABC, ab = AC, e is on AC, and the extension line of ad = AE, de intersects BC at point F
- 12. As shown in the figure, extend the edge BC of △ ABC to d so that CD = BC, take the midpoint F of AB and the edge DF intersect AC with E, and calculate the value of aeac
- 13. As shown in the figure, in RT △ ABC, if ∠ C = 90 °, a = 30 °, e is the point on AB, AE: EB = 4:1, EF ⊥ AC is in F, and FB is connected, then the value of Tan ⊥ CFB is equal to () A. 33B. 233C. 533D. 53
- 14. As shown in the figure, in △ ABC, ad is high, AE and BF are bisectors of angles. They intersect at point O, ∠ a = 50 ° and ∠ C = 60 ° to find ∠ DAC and ∠ boa
- 15. Ask four quadrant angle sine cosine tangent value is positive or negative
- 16. Given that alpha is the second quadrant angle, what quadrant angle is alpha What about half alpha
- 17. Given that alpha is the second quadrant angle, what is the second half of alpha
- 18. According to the relationship between tangent function and sine and cosine function, the tangent expression of alpha and beta with arbitrary angle is deduced The formula of Tan (alpha + beta) and Tan (alpha beta) That is Tan (alpha + beta)= Tan (alpha beta)=
- 19. In the isosceles right triangle ABC, the angle c = 90 ° D is the midpoint of BC, De is perpendicular to AB and E, and it is proved that ae-be = AC If it's not an isosceles triangle, there's another one.
- 20. In the triangle ABC, if a = 80, B = 100, and a = 45 degrees, how many solutions does the triangle have? Method of solving