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

It is proved that: as shown in the figure, am ⊥ BC is made in M through a, ∵ AB = AC, ∵ BAC = 2 ⊥ BAM, ∵ ad = AE, ∵ d = ∠ AED, ∵ BAC = 2 ⊥ BAM = 2 ⊥ D, ∵ BAM = D, ∵ DF ∥ am, ≁ am ⊥ BC, ≁ DF ⊥ BC

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1. It is known that AB is parallel to EF, CD, ad is parallel to BC, and BD is bisected
2. 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
3. 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
4. P is any point in the equilateral triangle ABC, PA = 3, Pb = 5, PC = 4, find the angle APC
5. 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
6. 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
7. 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
8. In the triangle ABC, the area of BDE, DCE and ACD are 90, 30 and 28 square centimeters respectively?
9. 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
10. 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
11. 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
12. 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
13. 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
14. Ask four quadrant angle sine cosine tangent value is positive or negative
15. Given that alpha is the second quadrant angle, what quadrant angle is alpha What about half alpha
16. Given that alpha is the second quadrant angle, what is the second half of alpha
17. 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)=
18. 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.
19. In the triangle ABC, if a = 80, B = 100, and a = 45 degrees, how many solutions does the triangle have? Method of solving
20. It is known that in the triangle ABC, a = 45 °, a = 2, C = √ 6