Mohon bantuu, terima kasih.

<p>Segitiga sama kaki memiliki 2 sisi yg sama panjang, maka jika</p><p>Keliling (K) = 98 cm</p><p>alas (a) = 40 cm</p><p>2 Sisi miring (b) &amp; (c) = (K - a) ÷2</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;= &nbsp;(98-40) ÷2</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;= 29 cm</p><p>&nbsp;</p><p>Karena segitiga sama kaki= 2× segitiga siku2</p><p>Tinggi (t) = √(sisi miring)² - (½×alas)²</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; = √b² - (½×a)²</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; = √29² - 20²</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; = √841 - 400</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; = √441</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; t &nbsp;= 21 cm</p><p>&nbsp;</p><p>Luas segitiga = ½ × alas × tinggi</p><p>L = ½ × 40 × 21</p><p>&nbsp; &nbsp;= 420 cm²</p><p>&nbsp;</p><p>Luas kaca yg di perlukan 420cm²</p>