In the given trapezium. ABCD , M and N are mid points of non parallel sides AD and BC. Find (i) MN if AB = 11 cm and DC = 8cm (ii) AB if DC =20cm and MN = 27 cm
Answers
Step-by-step explanation:
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Cᴏɴsᴛʀᴜᴄᴛɪᴏɴ -
Join DB.
Sᴏʟᴜᴛɪᴏɴ -
i) MN , if AB = 11 cm and DC = 8 cm.
=> AB || DC,
M and N are the midpoints of sides AD and BC respectively.
∴ MN || AB and MN || DC.
Now,
OM = 1/2 AB [mid point theorem]
=> 1/2 × 11
=> 11/2
=> 5.5 cm
And,
ON = 1/2 DC [mid point theorem]
=> 1/2 × 8
=> 4 cm.
∴ MN = OM + ON
=> MN = 5.5 + 4
=> MN = 9.5 cm ..(ans)
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ii) AB, if DC = 20 cm and MN = 27 cm.
=> Let AB = x.
We know that,
MN = 1/2 (AB + DC)
=> 27 = 1/2 (x+20)
=> 27×2 = x + 20
=> 54 - 20 = x
∴ x = 34 cm ..(ans)
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iii) DC, if MN = 15 cm and AB = 23 cm.
=> Let DC = x.
we know that,
MN = 1/2 (AB + DC)
=> 15 = 1/2 (23+x)
=> 15×2 = 23+x
=> 30-23 = x
∴ x = 7 cm ..(ans)
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@MissSolitary✌️
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