In the regular triangular prism abc-a1b1c1, if AB = 2 and a & nbsp; A1 = 1, then the distance from point a to plane a1bc is () A. 34B. 32C. 334D. 3
Let the distance from point a to plane a1bc be h, then the volume of the triangular pyramid va1 − ABC is va1 − ABC = VA − a1bc, that is, 13s △ ABC · Aa1 = 13s △ a1bc · h { 13 · 3 · 1 = 13 · 2 · h { H = 32
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- 1. It is known that each edge length of oblique triangular prism abc-a1b1c1 is 1, and the angle a1ab = angle a1ac = 60 degrees How to prove bcc1b1 as a square
- 2. As shown in the figure, it is known that all edges of the regular triangular prism abc-a1b1c1 are equal in length, and D is the midpoint of a1c1, then the sine value of the angle between the straight line AD and the plane b1dc is______ .
- 3. In the regular triangular prism abc-a1b1c1, if all edges are equal in length, then the tangent of the angle between the straight line CB1 and the plane aa1b1b is () A. Root 15 / 3 B. root 15 / 5 C. root 5 / 5 d. root 2
- 4. It is known that the lengths of the side edges and the bottom edges of the triangular prism abc-a1b1c1 are equal, and the projection of A1 on the bottom ABC is the midpoint D of the BC edge, then the cosine value of the angle formed by the out of plane line AB and CC1 is: A、(√3)/4 B、(√5)/4 C、(√7)/4 D、3/4 Please give me a picture of this problem. There are a lot of pictures in the process of solution
- 5. It is known that the side edge and the bottom edge of the triangular prism abc-a1b1c1 are equal, and the projection of A1 in the ground ABC is the center of ABC, What is the cosine of AB and CC1
- 6. It is known that the side edges and the bottom sides of the triangular prism abc-a1b1c1 are equal, and the projection D of A1 on the bottom ABC is the midpoint of BC, then the cosine value of the angle between AB and CC1 is? Trouble with space vector and solid geometry method to give solutions
- 7. It is known that the side edges of the triangular prism abc-a1b1c1 are equal to the sides of the bottom. The projection of A1 in the plane ABC is △ ABC It is known that the side edges and the bottom sides of the triangular prism abc-a1b1c1 are equal, and the projection of A1 in plane ABC is the center of △ ABC, then the sine value of the angle between Ab1 and plane ABC is △ ABC To process! Write a good reward to
- 8. In the triangle ABC, ∠ a = 80 degrees, the bisector of the outer angles of ∠ B and ∠ C intersects point O, and ∠ BOC?
- 9. In the triangle ABC, where ∠ a = 40 ° and O is the intersection of the bisectors of ∠ ABC and ∠ ACB, then ∠ BOC=______ .
- 10. It is known that in △ ABC, ∠ a = 60 ° and the bisectors of ∠ ABC and ∠ ACB intersect at point O, then the degree of ∠ BOC is 0______ Degree
- 11. In the straight triangular prism abc-a1b1c1, ∠ ACB = 90 ° Aa1 = AC = a, then the distance from point a to plane a1bc is?
- 12. In the triangular prism abc-a1b1c1, ab = AC = 2aa1, ∠ baa1 = ∠ caa1 = 60 °, D and E are the midpoint of AB and A1C respectively
- 13. In the regular triangular prism abc-a1b1c1, ab = 2, Aa1 = 1, find the distance from point a to plane a1bc
- 14. As shown in the figure, the inscribed circle O of RT △ ABC cuts the hypotenuse AB to D, cuts BC to F, and the extension line AC of Bo intersects at point E Prove Bo * BC = BD * be
- 15. The inscribed circle O of the right triangle ABC, the hypotenuse AB at point D, the tangent BC at point F, and the intersection AC of the extension line of Bo at point E
- 16. As shown in the figure, in △ ABC, e is a point on the edge of BC, EF is perpendicular to BC, intersects BA at D, intersects the extension line of Ca at F, if ad = AF, is △ ABC an isosceles triangle
- 17. In △ ABC, ad bisects ∠ BAC, intersects BC with D, EF ‖ ad, intersects AC with E, intersects the extension of BA with F. it is proved that △ AEF is an isosceles triangle
- 18. )As shown in the figure, it is known that ∠ ABC = 60 °, ACB = 50 °, Bi bisection ∠ ABC, CI bisection ∠ ACB, Bi and CI intersection at I, passing through point I as De, (1) calculate the degree of ∠ BIC (2) Guess the quantitative relationship among BD, CE and De, and explain the reason
- 19. In △ ABC, Bi bisection ∠ ABC, CI bisection ∠ ACB, be, CE are bisection lines of external angle, if ∠ a = 50 °, then ∠ I =? ° ∠ Ube =? ±
- 20. If a, B and C are three sides of △ ABC, the result of simplifying | a-b-c | + | b-c-a | + | C-A-B |, is () A. -a-b-cB. a+b+cC. a+b-cD. a-b+c