Question

In Fig. 9.43, if EC||AB, ∠ECD =70° and ∠BDO =20° , then ∠OBD is
A. 20°
B. 50°
C. 60°
D. 70°

Answer 1

Answer:

B.50°

Step-by-step explanation:

sum of 2 interior opposite angles is equal to the exterior opposite angle..since angle AOD is 70 and angle ODB is 20 angle OBD=50°

Answer 2

Given : In Fig , EC || AB, ∠ECD = 70° and ∠BDO = 20°

 

To find : ∠OBD  

Solution :  

Since, EC ‖ AB and, OC is a transversal.

∠ECD = ∠1  (Alternate angle)

∠1 = 70°  

∠1 + ∠3 = 180° (Linear pair)

70° + ∠3 = 180°

∠3 = 180° -  70°  

∠3 = 110°  

In ∆BOD ,  

∠BOD + ∠OBD + ∠BDO = 180°

∠3 + ∠OBD + 20° = 180°

110° + ∠OBD + 20° = 180°

130° + ∠OBD = 180°

∠OBD = 180° - 130°  

Hence, ∠OBD = 50°

Among the given options option  (B) 50°  is correct.

 HOPE THIS ANSWER WILL HELP YOU…

 

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In Fig. 8.128, if AB||CD, then the value of x is

A. 20°

B. 30°

C. 45°

D. 60°

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In Fig. 8.136, if CP || DQ, then the measure of x is

A. 130°

B. 105°

C. 175°

D. 125°

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