tolong di bantu ya kakak

[tex]sisi \: alas = \sqrt{ {26}^{2} - {24}^{2} } \\ = 10 \\ \\ 2(10 + 24 + 26) + 3t = 246 \\ 120 + 3t = 246 \\ t = \frac{246 - 120}{3} \\ t = 42[/tex]