As shown in the figure, in △ ABC, BD bisects ∠ ABC, de ⊥ AB in E, ab = 3cm, BC = 2.5cm, and the area of △ abd is 2cm2. Calculate the area of △ ABC

As shown in the figure, in △ ABC, BD bisects ∠ ABC, de ⊥ AB in E, ab = 3cm, BC = 2.5cm, and the area of △ abd is 2cm2. Calculate the area of △ ABC

In △ abd, ∵ s △ abd = 12ab · De, ab = 3cm, s △ abd = 2cm2, ∵ de = 43cm (2 points) make DF ⊥ BC through D, and make f. ∵ BD bisection ⊥ ABC, de ⊥ AB, DF ⊥ BC, ≁ de = DF, ≁ DF = 43cm (4) in △ BCD, BC = 2.5cm, DF = 43cm  s △ BCD = 12bc · DF = 53 (CM) 2 (6 points) ∵ s △ ABC = s △ abd + s △ BCD, ∵ s △ ABC = 2 + 53 = 113 (CM) 2 (8 points)

As shown in the figure, at △ ABC, ∠ C = 90 °, ad is the bisector of ∠ cab, CD = 4cm, then the distance from point d to AB is________
The picture can't be put up. It's not infinite

It's four centimeters. The triangle is congruent!

It is known that in △ ABC, Tana = - 512, then the value of sina is ()
A. 15B. 513C. −15D. −513

∵ in △ ABC, a ∈ (0, π), ∵ Tana = − 512 < 0, ∵ a ∈ (π 2, π) ∵ Tana = − 512, ∵ sin2acos2a = 25144, ∵ sin2a1 − sin2a = 25144 ∵ sin2a = 25169 ∵ Sina = 513

The geometry problem that can't be solved: given that D and E are the points on the sides AC and ab of triangle ABC, and BD = BC, ad = de = EB, find the degree of angle A
I know the answer is 45 degrees, but I just don't know how to find it. Please write down the solving process in detail. Thank you very much!
Really no master can do it, I really need the answer, although not a lot of money

There are infinitely many solutions, and the value range of angle a is greater than 0 and less than 60
Draw a picture for yourself. My proof is as follows
Because BD = BC, ad = de = EB, the triangles ade, BDE and BCD are isosceles triangles
So angle a = angle AED, angle DBE = angle BDE, angle c = angle BDC
Because the angle AED is the outer angle of the triangle BDE, the angle a = 2 times the angle DBE. 1
Because angle BDC is the outer angle of triangle abd, angle d = 1.5 times angle A.2
Let a be x, C be y and ABC be Z
According to 1,2, the equation y = 1.5x.3 can be deduced
According to the theorem of triangle inner angle sum, the equation x + y + Z = 180.4 can be deduced
According to the known conditions, we can only deduce two cubic equations, so angle a has infinite solutions
Because angle a + angle c + angle abd + angle CBD = 180
So angle a + angle c + angle abd = 3 times angle a < 180 degrees, so angle a < 60 degrees
For example, when angle a = 30 degrees, angle abd = 15, angle c = 45, angle CBD = 90, angle a + angle abd + angle CBD + angle c = 180
When angle a = 40 degrees, angle abd = 20, angle c = 60, angle CBD = 60, angle a + angle abd + angle CBD + angle c = 180
When angle a = 45 degrees, angle abd = 22.5, angle c = 67.5, angle CBD = 45, angle a + angle abd + angle CBD + angle c = 180
But when angle a = 60 degrees, angle c = angle BDC = 90 is obviously wrong

As shown in the figure, in △ ABC, ab = AC, BD = BC, ad = de = EB, then ∠ A is ()
A. 30°B. 45°C. 60°D. 20°

Let a = x, ∵ ad = De, ∵ DEA = - a = x, ∵ de = EB, ∵ EBD = - EDB = X2, ∵ BDC = - A + - DBA = x + x2 = 3x2, ∵ AB = AC, BD = BC, ∵ C = - BDC = - ABC = 3x2,