OKAY

Geometry Level 1

As illustrated in the above diagram, four points O = ( 1 , 3 ) , K = ( a , b ) , A = ( c , d ) , Y = ( 2 , 7 ) O = (1,-3), K = (a,b), A=(c,d), Y= (2,7) lie on the same line segment. If O K = K A = A Y , OK=KA=AY, what is the value of a + b + c + d ? a+b+c+d?


The answer is 7.

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2 solutions

Using Section Formula .

In O A \overline{OA} .
1 + c 2 = a \Rightarrow \dfrac{1+c}{2}=a ..... ( 1 ) (1)

3 + d 2 = b \Rightarrow \dfrac{-3+d}{2}=b ..... ( 2 ) (2)

Now, In K Y \overline{KY} .
a + 2 2 = c \Rightarrow \dfrac{a+2}{2}=c ..... ( 3 ) (3)

b + 7 2 = d \Rightarrow \dfrac{b+7}{2}=d ..... ( 4 ) (4) .

Adding ( 1 ) , ( 2 ) , ( 3 ) (1),(2),(3) and ( 4 ) (4) .
a + b + c + d = a + b + c + d + 7 2 \Rightarrow a+b+c+d=\dfrac{a+b+c+d+7}{2}
a + b + c + d = 7 . \Rightarrow a+b+c+d=\boxed{7}.

Used same approach .

Vignesh Rao - 5 years, 5 months ago

First you can find the coordinates of either K or A by dividing line segment in ratio 1:2 or 2:1 respectively. Then bisect the double length segment to get final coordinate pair.

very smart and tricky way enjoyed this method

amulya Peerla - 2 years, 7 months ago

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