Question

Nomor 123 gmna ya bang/kak ?? Mohon penjelasannya

Answer 1

AB = BC = AC = x => segitiga sama sisi
CD = tinggi segitiga = √(AC^2 - AD^2)
= √(x^2 - ((1/2)x)^2)
= √(x^2 - (1/4)x^2)
= √((3/4)x^2)
= (1/2)x√3

AB + BC + AC + CD = 66
=> x + x + x + (1/2)x √3 = 66
=> 3x + (1/2)x√3 = 66
=> 6x + x√3 = 132
=> x(6 +√3) = 132
=> x = 132/(6 + √3)
=> x = 132/(6 + √3) . (6 - √3)/(6 - √3)
=> x = 132(6 - √3) / (36 - 3)
=> x = 132(6 - √3)/33
=> x = 4(6 - √3)
=> x = 24 - 4√3