Question

question no. 8,9,10,11

Answer 1

8).sum of adjacent angles = 180°
2x+5+3x=180
5x= 175
x= 35°
9).2a +3b–10= 180
2a+3b=190
and,4a– 3b =20
adding both:- 6a= 210
a= 35,so angle BOC= 70°
and ,b=40,so angle AOC =3×40-10=110°
10).3x+7+x+5+40= 180°
4x+52=180
4x=128
x=32.now putting the values of x and u can solve.
11).4x–5+45= 180
4x = 140
x= 35
now,45+x+z= 180
45+35+z=180
z=100
and,x+y+z=180
35+100+y=180
y=45

Answer 2

Hi Friend !
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8)sum of two adjacent angles is 180 degrees
so , 2x+5+3x= 180 
       5x+5      = 180 
       5(x+1)   =  180
         x+ 1    = 180/5
         x         = 36-1 = 35
         x         = 35 degrees
So one angle is 2(35)+5 = 75*
     other angle is 3(35)   = 105*
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9)In the given figure :
 angle BOC + Angle AOC = 180 (linear pair)
    3b-10       +  2a               =180
   2a+3b                              =190 ___________________(1)
also ,4a-3b                        =  20____________________(2)[Given]
MBS by 2 in Eqn 1 
we get  4a +6b                 = 380 ___________________(3)
Eliminating equation 3rd and 2nd 
  4a+6b=380 
-4a +3b= -20 
        9b=  360 
          b=   40
   put the value of b in 2nd equation we get,
4a-3(40)=20 
4a          = 20 +120 
4a          = 140 
a            =  140/4
a            =   35
so the angles are 3b-10 = 110*
                              2a       =  70*
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10) In the figure 
angle COE+BOE +DOB= 180 *[Linear Pair]
3x+7  + x+5   +40           = 180*
4x +52                            = 180*
4(x+13)                          = 180
x+13                              =  180/4  = 45
x                                    = 45-13
                          x          = 32 
so the angle COE = 3x+7= 103*
                      BOE = x+5  = 37*
                      COB= 103+37= 140*
                      AOC = 180- COB = 180-140 = 40 *
                      BOC = AOD = 140*(VOA)
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11) In the adjoining figure 
     Angle AOC+BOC+BOD+EOD +EOA= 360*
     45 + 4x-5 + x+y + z                             = 360*___________(1)
     45 +4x-5  = 180________(2) [LPA's]
     40 +4x     = 180 
      4(10+x)   = 180 
         10 + x  =   45 
                  x =    35* 
BOC = 4x-5 = 135 * 
 also,y + BOC= 180*
          y           =  45 *
also x+y +z    =  180*
  35* + 45* +z = 180* 
 z                    =  180-80 = 100*
so, x=35*
       y= 45*
       z= 100*
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