A) \[50{}^\circ \]
B) \[60{}^\circ \]
C) \[70{}^\circ \]
D) \[80{}^\circ \]
Correct Answer: C
Solution :
Let required angle be q From geometry of figure \[In\,\Delta \,A\,B\,C\,;\,\,a=180{}^\circ \left( 60{}^\circ +40{}^\circ \right)=80{}^\circ \] \[\Rightarrow \,\,\beta ~=90{}^\circ 80{}^\circ =10{}^\circ \] \[In\,\Delta \,A\,B\,D\,;\,\angle A=60{}^\circ ,\angle B=(a+2\beta )\] \[=(80+2\times 10)=100{}^\circ \,and\,\angle D=(90{}^\circ \theta )\] \[\because \,\angle A+\angle B+\angle D=180{}^\circ \] \[\Rightarrow \,\,60{}^\circ +100{}^\circ +(90{}^\circ \theta )=180{}^\circ \,\,\Rightarrow \theta =70{}^\circ \]You need to login to perform this action.
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