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七年级数学解答题一般
题目
已知:如图,直线ABABCDCD相交于点OO,OECDOE\bot CD,COA+BOD=50\angle COA+\angle BOD=50^{\circ},则EOB=______.\angle EOB=\_\_\_\_\_\_^{\circ}.
知识点:余角和补角、垂线章节:第6章 平面图形的初步认识 / 6.3 相交线

答案与解析

答案

COA+BOD=50\because \angle COA+\angle BOD=50^{\circ}
BOD=COA\angle BOD=\angle COA
COA=BOD=25\therefore \angle COA=\angle BOD=25^{\circ}.
OECD\because OE\bot CD
EOD=90\therefore \angle EOD=90^{\circ}
EOB=90BOD=65\therefore \angle EOB=90^{\circ}-\angle BOD=65^{\circ}
故答案为:6565.

解析

COA+BOD=50\because \angle COA+\angle BOD=50^{\circ}
BOD=COA\angle BOD=\angle COA
COA=BOD=25\therefore \angle COA=\angle BOD=25^{\circ}.
OECD\because OE\bot CD
EOD=90\therefore \angle EOD=90^{\circ}
EOB=90BOD=65\therefore \angle EOB=90^{\circ}-\angle BOD=65^{\circ}
故答案为:6565.

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