In the rectangular coordinate system with o as the origin, point a (4, - 3) is the right angle vertex of △ OAB In the rectangular coordinate system with o as the origin, point a (4, - 3) is the right angle vertex of △ OAB. It is known that | ab | = 2 | ab |, and the ordinate of point B is greater than zero Find the cosine value of the obtuse angle formed by the middle line on the two right angle sides of RT △ OAB It's a vector that can't be typed

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• 1. There is a RT triangle ABC, BC = 2, AC = radical 3, ab = 1. Put it in the rectangular coordinate system, BC is on the x-axis, and the right angle vertex is on the y = radical 3 / X image, and find the coordinates of point C
• 2. In RT △ ABC, if the hypotenuse AB = 5 and the right angle BC = 5, then the area of △ ABC is______ ．
• 3. There is a RT △ ABC, a = 90 °, B = 60 ° and ab = 1, which is placed in the rectangular coordinate system Let the hypotenuse BC be on the x-axis and the right angle vertex a be on the inverse scale function y = radical 3 / x, and calculate the coordinate of point C (I will solve this problem, and the key is the next one). If we change the conditional hypotenuse BC on the x-axis to hypotenuse BC on the coordinate axis and point a on the image y = radical 3 / x, then calculate the coordinate of point C If it's OK, I'll give you extra points and help me solve it by next Monday
• 4. In the known isosceles triangle ABC, the angle a = 80 ° is used to find the degree of the other two angles step
• 5. In the isosceles triangle ABC, the opposite sides of angle a, angle B and angle c are a, B and C respectively. A = 3 is known B and C are the two real roots of the quadratic + MX + 2-1 / 2m = 0 of the equation x about X. find the perimeter of △ ABC
• 6. In triangle ABC, angle a = 2, angle B. when angle c =? It is an isosceles triangle Such as the title
• 7. Triangle ABC is isosceles triangle, and angle a is 36 degrees Find the value of BC / ab
• 8. In the isosceles triangle ABC, ab = AC, angle a = y degree, angle B = x degree 1. The function analytic expression of Y with respect to X 2. The value range of independent variable x 3. Vertex degree when x = 35
• 9. In the isosceles triangle ABC, if angle a = 36 degrees, what is angle B
• 10. The ABC angle a of isosceles triangle is 100 degrees An isosceles triangle ABC, angle a is 100 degrees, extend AB to D, make ad = BC, calculate the degree of angle BCD!
• 11. In the rectangular coordinate system, a (4, - 3) is the right angle vertex of OAB, and / AB / = 2 / OA /, the coordinates of vector AB are obtained //Represents absolute value, OAB is triangle
• 12. In the rectangular coordinate system with o as the origin, point a (4, - 3) is the right angle vertex of △ OAB. It is known that | ab | = 2 | OA |, and the ordinate of point B is greater than 0 1. Find the coordinates of vector ab 2. Find the equation of circle X & # 178; - 6y + Y & # 178; + 2Y = 0 with respect to the circle with OB symmetry
• 13. As shown in the figure, △ ABC, ad is the midline, AE is the bisector of angles, CF ⊥ AE is f, ab = 5, AC = 2, find the length of DF
• 14. As shown in the figure, in △ ABC, ∠ ACB = 90 °, AC = BC, point D is the midpoint of AB, AE = CF
• 15. As shown in the figure, D, e and F are respectively the midpoint of △ ABC, G is the midpoint of AE, and be intersects DF and DG at P and Q, then PQ: be=______ ．
• 16. As shown in the figure, known isosceles △ ABC, AC = BC = 10, ab = 12, take BC as diameter, make ⊙ o intersection AB point D, intersection AC at point G, DF ⊥ AC, perpendicular foot is f, intersection CB extension line at point E. (1) prove: straight line ef is tangent line of ⊙ o; (2) find the value of sin ∠ a
• 17. Let D and E be the points on the sides AB and BC of the triangle ABC, ad = 1 / 2Ab and be = 2 / 3bC. If de = in 1ab + in 2Ac, then in 1 + in 2 =? (both in 1 and in 2 in the title denote symbols,
• 18. In RT triangle ABC, if ∠ C = 90 °, AC = 6, BC = 8, and G is the center of gravity of △ ABC, then CG =? RT
• 19. As shown in the figure, in RT △ ABC, ∠ ACB = 90 °, ab = 10, BC = 8, point d moves on BC (does not move to B, c), de ‖ AC, intersects AB with E, let BD = x, the area of △ ade is y. (1) find the functional relationship between Y and X and the value range of independent variable x; (2) when x is the value, the area of △ ade is the largest? What is the maximum area?
• 20. As shown in the figure, in RT △ ABC, ∠ a = 90 °, ab = AC = 2, point D is the midpoint of BC side, point E is a moving point on AB side (not coincident with a and b), DF ⊥ de intersects AC at F Let be = x, FC = y （1）DE=DF (2) The functional relation of Y with respect to X and the definition field of X are written out (3) When writing the value of X, EF / / BC