tolong dibantu ya lengkap dengan rumusnya

[tex] {ac}^{2} = {ab}^{2} - {bc}^{2} \\ {ac }^{2} = {25}^{2} - {20}^{2} \\ = 625 - 400 \\ {ac}^{2} = 225 \\ ac = \sqrt{225} \\ =ac = 15[/tex]
luas = (a* t )/ 2 = (25 * 20) / 2 = 250 cm ^2