udah nyoba dikerjain sendiri eh gak ketemu jawabannya,, kakak ada ada yang bisa gak,, tolong jabarkan yh..

ET = HT = 1/2 HF = 1/2 9 akar2 = 9/2 akar2
EA = 9

AT² = (9akar2/2)² + 9²
AT² = 81/2 + 81
AT² = 243/2
AT² = 121,5
AT = 9akar6/2

cos EAT = EA/AT
cos EAT = 9/9akar6/2
cos EAT = 1/3 akar 6

jawaban E