In triangle ABC, if angle a = 36 degrees, ab = AC, BD bisector angle ABC, de parallel BC, then isosceles triangle has ()

In triangle ABC, if angle a = 36 degrees, ab = AC, BD bisector angle ABC, de parallel BC, then isosceles triangle has ()

5 (including triangle ABC)

In the isosceles triangle ABC, ab = AC, angle a = 36 °, BD bisects angle ABC, intersects AC at point D. if AB = 2, then the length of ad is?

AB = AC, so ∠ ABC = ∠ C, because ∠ a = 36, ∠ ABC + ∠ C = 144, so ∠ ABC = ∠ C = 72bd bisecting ∠ ABC, then ∠ abd = ∠ CBD = 36, so ∠ abd = ∠ CBD = ∠ a, ad = BD △ ABC and △ BDC, in ∠ a = ∠ CBD, ∠ C = ∠ C, so △ ABC ∽ BDC. Because AB = AC, so BD = BC = ad, let ad be x, then BC be X

In △ ABC, ab = AC, ∠ a = 36 degrees, BD bisecting ∠ ABC has an isosceles triangle

Three isosceles triangles △ abd △ BCD △ ABC