Bantu jawab 🙏

<p>Diketahui <strong>∠ADC adalah sudut keliling</strong> dan <strong>∠AOC adalah sudut pusat</strong>, besar sudut keliling adalah setengah dari besar sudut pusat, maka:</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;∠ADC = 1⁄2 x ∠AOC &nbsp;&nbsp;</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; = 1⁄2 x 138°</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;∠ADC = 69°</p><p>&nbsp;</p><p>Pada segiempat tali busur ABCD&nbsp;</p><p>Besar dari ∠ABC + ∠ADC = 180°</p><p>maka besar &nbsp; ∠ABC + 69° = 180°</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;∠ABC = 180° - &nbsp;69°&nbsp;</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;∠ABC = 111°</p><p>&nbsp;</p><p>Besar dari &nbsp;∠ABC adalah 111° (E.)</p>