In Fig. 8.44, AOF and FOG form a linear pair.

EOB = FOC = 90° and DOC = FOG = AOB = 30°



(i) Find the measures of FOE, COB and DOE.


(ii) Name all the right angles.


(iii) Name three pairs of adjacent complementary angles.


(iv) Name three pairs of adjacent supplementary angles.


(v) Name three pairs of adjacent angles.

(i) Say,

FOE = x


DOE = y


BOC = z


AOF + 30o = 180o (AOF + FOG = 180o)


AOF = 150o


AOB + BOC + COD + DOE + EOF = 150o


30o + z + 30o + y + x = 150o


x + y + z = 90o(i)


Now,


FOC = 90o


FOE + EOD + DOC = 90o


x + y + 30o = 90o


x + y = 60o (ii)


Using (ii) in (i), we get


x + y + z = 90o


60o + z = 90o


z = 30o (BOC = 30o)


BOE = 90o


BOC + COD + DOE = 90o


30o + 30o + DOE = 90o


DOE = 30o


Now, we have


x + y = 60o


y = 30o


FOE = 30o


(ii) Right angles are:


DOG, COF, BOF, AOD


(iii) Three pairs of adjacent complimentary angles are:


AOB, BOD


AOC, COD


BOC, COE


(iv) Three pairs of adjacent supplementary angles are:


AOB, BOG


AOC, COG


AOD, DOG


(v) Three pairs of adjacent angles are:


BOC, COD


COD, DOE


DOE, EOF


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