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Question: If \(ABCDEF\) is a regular hexagon, then \(\overset{\rightarrow}{AD} + \overset{\rightarrow}{EB} + \...

If ABCDEFABCDEF is a regular hexagon, then AD+EB+FC=\overset{\rightarrow}{AD} + \overset{\rightarrow}{EB} + \overset{\rightarrow}{FC} =

A

O\overset{\rightarrow}{O}

B

2AB2\overset{\rightarrow}{AB}

C

3AB3\overset{\rightarrow}{AB}

D

4AB4\overset{\rightarrow}{AB}

Answer

4AB4\overset{\rightarrow}{AB}

Explanation

Solution

We have AD+EB+FC\overset{\rightarrow}{AD} + \overset{\rightarrow}{EB} + \overset{\rightarrow}{FC}

=(AB+BC+CD)+(ED+DC+CB)+FC(\overset{\rightarrow}{AB} + \overset{\rightarrow}{BC} + \overset{\rightarrow}{CD}) + (\overset{\rightarrow}{ED} + \overset{\rightarrow}{DC} + \overset{\rightarrow}{CB}) + \overset{\rightarrow}{FC}

=AB+(BC+CB)+(CD+DC)+ED+FC\overset{\rightarrow}{AB} + (\overset{\rightarrow}{BC} + \overset{\rightarrow}{CB}) + (\overset{\rightarrow}{CD} + \overset{\rightarrow}{DC}) + \overset{\rightarrow}{ED} + \overset{\rightarrow}{FC}

=AB+O+O+AB+2AB\overset{\rightarrow}{AB} + \overset{\rightarrow}{O} + \overset{\rightarrow}{O} + \overset{\rightarrow}{AB} + 2\overset{\rightarrow}{AB}

= 4AB4\overset{\rightarrow}{AB} [ED=AB,FC=2AB]\lbrack\overset{\rightarrow}{ED} = \overset{\rightarrow}{AB},\overset{\rightarrow}{FC} = 2\overset{\rightarrow}{AB}\rbrack