Triangles [NEW] — Maths STD 9 — Question

2. 50º

Solution:

EC || AB And, CD is transverse to it.

Now $\angle\text{ECD}=\angle\text{AOD}=70^\circ$ (Corresponding angles)

 In $\triangle\text{OBD}$

$\angle\text{OBD}+\angle\text{BOD}+\angle\text{ODB}=180^\circ$

$\angle\text{BOD}=180^\circ-\angle\text{AOD}=180^\circ-70^\circ=110^\circ$

So $\angle\text{OBD}=180^\circ-\angle\text{BOD}-\angle\text{ODB}$

$=180^\circ-110^\circ-20^\circ$

$=50^\circ$