Mathematics

Mark the correct alternative of the following.In figure, if AOB and COD are straight lines. Then, $x+y=?$

$140$

SOLUTION

In figure, $\angle AOC = \angle BOD$                 (VOA)
$\angle AOC = 3x^o$
$\angle AOD = y^o$                 (VOA)
$y^o = (7x - 20)^o$
$\angle AOC + \angle COB + \angle BOD + \angle AOD = 360^o$
$3x + (7x - 20) + 3x + (7x - 20) = 360^o$
$3x + 7x - 20 + 3x + 7x - 20 = 360^o$
$20x - 40 = 360^o$
$20x = 360^o + 40$
$20x = 400^o$
$x = 20^o$
So, $\angle BOD = 3x^o = 3 \times 20^o = 60^o$
$\angle BOC = y^o = 7x - 30 = 7 \times 20^o - 20= 120^o$
$x + y = 20 + 120 = 140^o$

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Single Correct Medium Published on 09th 09, 2020
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