As shown in the figure, in RT △ ABC, ∠ C = 90 °, am is the middle line on the side of BC, sin ∠ cam = 35, then the value of tanb is () A. 32B. 23C. 56D. 43
In RT △ ACM, sin ∠ cam = CMAM = 35, let cm = 3x, then am = 5x. According to Pythagorean theorem, AC = AM2 − cm2 = 4x, and M is the midpoint of BC, ﹥ BC = 2cm = 6x, in RT △ ABC, tanb = ACBC = 4x6x = 23
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- 1. Known: as shown in the figure, in triangle ABC, angle ACB = 90, AC = BC, CD / / AB, and ab = ad
- 2. If △ ABC ∽ CAD, ∠ ACB = ∠ ADC = 90, BC = a, AC = B, ab = C, then CD is equal to Please use letters Thank you in advance
- 3. On the site of right triangle ABC, the angle bisector AE of ∠ B = 90 ° AB = AC intersects at point E Party A and Party B start from a at the same time and go along the AC and A-B-E lines at the same speed. Party A's destination is C and Party B's destination is e. please judge which of Party A and Party B arrive at their respective destinations first? And explain the reason
- 4. As shown in the figure, D is the midpoint of the waist AC of the isosceles right triangle ABC, connecting BD, making AE through a, vertical BD, side BC at e, try to explain, ∠ ADB = ∠ CDE
- 5. In equilateral △ ABC, points D and E are on edges BC and ab respectively, and BD = ae
- 6. As shown in the figure, in the triangle ABC, ad is vertical to BC, be is vertical to AC, CF is vertical to AB, and the perpendicular feet are D, e, F. BC equals 16, ad equals 3, CF equals 6. Calculate the circumference of ABC
- 7. As shown in the figure, the perimeter of the right angle △ ABC is 18. There are five small right triangles in it, and the right sides in the same direction are parallel to each other. Find the sum of the perimeter of the five small right triangles
- 8. In RT △ ABC, the bisector be, the perpendicular BC, the perpendicular foot E and BC = 20 are used to calculate the perimeter of △ Dec
- 9. In △ ABC, ab = AC, the vertical bisector of AB intersects at point D and AC intersects at point e. it is known that the perimeter of △ BCE is 8 and ac-bc = 2. The lengths of AB and BC are obtained
- 10. In the triangle ABC, if AB = 3, AC = 8, the length of BC is odd, try to find the perimeter of the triangle ABC
- 11. In known acute triangle ABC, sin (a + b) = 3 / 5, sin (a-b) = 1 / 5 In known acute triangle ABC, sin (a + b) = 3 / 5, sin (a-b) = 1 / 5 (1) Verification: Tan a = 2tanb; (2) Let AB = 3, find the height on the edge of ab
- 12. In the triangle ABC, the angle c = 90 degrees, BC = AC = 2, D is the midpoint of the AC side, find sin angle, Tan angle DBA
- 13. In the triangle ABC, ADA is perpendicular to D, angle bad = a, angle CAD = B= sina.sinb + cosa.sinb
- 14. In △ ABC, ∠ C = 90 °, De is the vertical bisector of AB on the line side, and the degree ratio of ∠ DAE to ∠ DAC is 2:1, so the degree of ∠ B can be calculated
- 15. As shown in the figure, in △ ABC, ∠ C = 90 °, the vertical bisector of AB intersects at point D, AB intersects at point E, the degree ratio of ∠ DAE and ∠ DAC is 2:1, and the degree of ∠ B is calculated
- 16. In △ ABC, the vertical bisector of AB intersects BC at point D, and the vertical bisector of AC intersects BC at point EBC = 12cm
- 17. If s △ abd = 1 / 2S △ ACD, then AB: AC=
- 18. As shown in the figure, in △ ABC, we prove: (1) if ad is the bisector of ∠ BAC, then s △ abd: s △ ACD = AB: AC; (2) let d be a point on BC to connect ad, if s △ abd: s △ ACD = AB: AC, then ad is the bisector of ∠ BAC
- 19. In the triangle ABC, angle a = 96 degrees, extend BC to D, and the bisector of angle ABC and angle ACD intersects at point A1, The bisector of angle a1bc and angle a1cd intersects at point A2, and so on, the bisector of angle ANBC and angle ancd intersects at point an + 1 Problem 1, find angle A1, angle A2, angle A3 2. Conjecture the formula of degree of angle an (n is a positive integer) 3. Use your conjectured formula to find the degree of angle an
- 20. As shown in the figure, in the rectangular ABCD, AE ⊥ BD, e is the perpendicular foot, ∠ DAE: ∠ BAE = 1:2, then ∠ CAE=______ Degree