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As shown in the figure, in △ ABC, the vertical bisector of ∠ C = 90 ° AB intersects AC at D, and the perpendicular foot is e. if ∠ a = 30 ° de = 2, the degree of ∠ DBC is______ The length of CD is______ ．
∵ De is the vertical bisector of AB, ∵ ad = BD, ≌ ADB is isosceles triangle, ∵ DBA = ∠ a = 30 °, ∵ CBD = 60 ° - 30 ° = 30 °, ≌ RT △ CDB ≌ RT △ DEB, ≌ CD = de = 2
As shown in the figure, in △ ABC, ∠ a = 50 ° AB = AC, and the vertical bisector De of AB intersects AC at D, then the degree of ∠ DBC is ()
A. 15°B. 20°C. 30°D. 25°
The solution is known, ab = AC ﹥ a = 50 °, ab = AC ﹥ ABC = ﹥ ACB = 65 ° and ∵ De is vertical and bisecting ab ﹥ DB = ad ﹥ abd = ﹥ a = 50 ﹥ DBC = ﹥ ABC - ﹥ abd = 65 ° - 50 ° = 15 °. So a is selected
As shown in the figure, in △ ABC, ∠ a = 50 ° AB = AC, and the vertical bisector De of AB intersects AC at D, then the degree of ∠ DBC is ()
A. 15°B. 20°C. 30°D. 25°
The solution is known, ab = AC ﹥ a = 50 °, ab = AC ﹥ ABC = ﹥ ACB = 65 ° and ∵ De is vertical and bisecting ab ﹥ DB = ad ﹥ abd = ﹥ a = 50 ﹥ DBC = ﹥ ABC - ﹥ abd = 65 ° - 50 ° = 15 °. So a is selected
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