Cho tam giác ABCD. Từ một điểm E trên cạnh AC vẽ đường thằng song song với BC cắt AB tại F và đường thằng song song với AB cắt BC tại D. Giả sử AE=BF a) Chứng minh tam giác AED cân
b)Chứng minh AD là phân giác của góc A

hi friend

here is your answer

there are two angles that are alternate interior angle with angle 9

the angle 15 and angle 7 are alternate interior angle with angle 9.

hope it is for you so mark my answer as a brainliest

all but the second one

step-by-step explanation:

cuz that one goes over 180

mark brainliest

answer: 204

step-by-step explanation:

we are told that the revenue is

x⋅(4080−10x)=−10x^2+4080x

this is a quadratic function, so to maximize it we should find the x-value of its vertex. recall that the x-value of the vertex of the parabola ax^2+bx+c is given by the formula −b/2a.

so in this case, we have a=−10 and b=4080, so the x-value of the vertex is

−b/2a= −(4080)/2(−10)=204