Practicing Success
ABCD is a cyclic quadrilateral. $\mathrm{AB}$ and $\mathrm{DC}$ meet at $\mathrm{F}$, when produced. $\mathrm{AD}$ and $\mathrm{BC}$ meet at $\mathrm{E}$, when produced. If $\angle \mathrm{BAD}$ $=68^{\circ}$ and $\angle \mathrm{AEB}=27^{\circ}$, then what is the measure of $\angle \mathrm{BFC}$ ? |
27° 22° 17° 15° |
17° |
\(\angle\)BAE + \(\angle\)BEA + \(\angle\)ABE = 180 = 68 + 27 + \(\angle\)ABE = 180 = 95 + \(\angle\)ABE = 180 = \(\angle\)ABE = (180 - 95) = \(\angle\)ABE = \({85}^\circ\) Now, \(\angle\)ABE + \(\angle\)CBF = 180 (linear pair) = 85 + \(\angle\)CBF = 180 = \(\angle\)CBF = (180 - 85) = \(\angle\)CBF = 95 Now, \(\angle\)BAE + \(\angle\)BCD = 180 = 68 + \(\angle\)BCD = 180 = \(\angle\)BCD = (180 - 68) = \(\angle\)BCD = \({112}^\circ\) Now, \(\angle\)BCD + \(\angle\)BCF = 180 = 112 + \(\angle\)BCF = 180 = \(\angle\)BCF = (180 - 112) = \(\angle\)BCF = \({68}^\circ\) Now, In \(\Delta \)BCF \(\angle\)BCF + \(\angle\)CBF + \(\angle\)BFC = 180 = 68 + 95 +\(\angle\)BFC = 180 = 163 + \(\angle\)BFC = 180 = \(\angle\)BFC = (180 - 163) = \(\angle\)BFC = \({17}^\circ\) Therefore, answer is \({17}^\circ\). |