Question

如图,在三角形abc中,角acb=90度,cd垂直ab于点d.已知角b+角acd=110度,求角a的度数.

Answer 1

∠ACD + ∠B = 110°__i

∠DCB + ∠B = 90°___ ii

∠DCB + ∠ACD = 90°___iii

ii - iii,∠B - ∠ACD = 0°

∠B = ∠ACD

i,2∠ACD = 110°

∠ACD = 55°

∠A + ∠ACD = 90°

∠A + 55° = 90°

∠A = 35°

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