tolong bantu no.19,20,dan21 beserta caranya

21.
t² = s² - r²
= 13² - 5²
= 169 - 25
= 144 = 12

r² = s² - t²
= 20² - 12²
= 400 - 144
= 256 = 16

alas = 16 - 5 = 11

L = a × t ½
= 11 × 12 ½
= 132 ½
= 66 cm²


Jawaban = d

GL!