no 25 & 26 tolong kasih caranya ya trims

25. b. (gatau lagi ya)
26. L = 2 × 3/4.πr² + r²
320 = 6/4 × 22/7r² + r²
320 = 3/2 × 22/7r² + r²
320 = 66/14r² + 7/7r²
320 = 33/7r² + 7/7r²
320 = 40/7r²
r² = 320 × 7/40
r² = 56cm²