）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

&Nbsp; as shown in the figure, (1) ∠ 1 = 1 / 2 ∠ ABC = 30 °, ∠ 4 = 1 / 2 ∠ ACB = 25 °, ∠ BIC = 180 - (∠ 1 + ∠ 2) = 125 ° & nbsp; (2) de = BD + CE, for the following reasons: ∫ de ‖ BC, ∫ 1 = ∠ 3, and ∫ 1 = ∠ 2, ∫ 2 = ∠ 3, ∫ BD = Di, similarly CE = Ci, de = Di + EI = BD + CE

RELATED INFORMATIONS

1. 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
2. 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
3. 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
4. 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
5. In the regular triangular prism abc-a1b1c1, ab = 2, Aa1 = 1, find the distance from point a to plane a1bc
6. In the triangular prism abc-a1b1c1, ab = AC = 2aa1, ∠ baa1 = ∠ caa1 = 60 °, D and E are the midpoint of AB and A1C respectively
7. In the straight triangular prism abc-a1b1c1, ∠ ACB = 90 ° Aa1 = AC = a, then the distance from point a to plane a1bc is?
8. 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
9. 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
10. 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______ ．
11. In △ ABC, Bi bisection ∠ ABC, CI bisection ∠ ACB, be, CE are bisection lines of external angle, if ∠ a = 50 °, then ∠ I =? ° ∠ Ube =? ±
12. 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
13. Note that the lengths of the three sides of the triangle ABC are a, B, C. simplify the algebraic formula ia-b-ci + ia-b + CI + Ia + b-ci
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