Answer:
Surface area of triangular prism = 528
Explanation:
Surface area of triangular prism = (Base x Height) + 2 (length x side) + (length x base)
SA = bh + 2Ls + Lb
Putting given values : b = Y = 5 , h = 9 , s = x = 9 , L = z = 21
(5 x 9) + (2 x 21 x 9) + (21 x 5)
= 45 + 378 + 105
528