A) \[{{160}^{{}^\circ }}\]
B) \[{{150}^{{}^\circ }}\]
C) \[{{120}^{{}^\circ }}\]
D) \[{{135}^{{}^\circ }}\]
Correct Answer: A
Solution :
(a): \[\angle ABC=\angle BCD\text{ }as\text{ }AB\parallel CD\] \[\angle BCD={{60}^{{}^\circ }}\] \[\angle ECD={{60}^{{}^\circ }}-\angle BCE\] \[={{60}^{{}^\circ }}-{{40}^{{}^\circ }}={{20}^{{}^\circ }}\] \[\angle CEF+\angle ECD={{180}^{^{{}^\circ }}}\] \[\angle CEF={{180}^{{}^\circ }}-\text{ }{{20}^{{}^\circ }}={{160}^{{}^\circ }}\]You need to login to perform this action.
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