tolong bantu yah beserta caranya

Diketahui :
- AE = 3 cm
- ED = 5 cm
- AD = 3 cm + 5 cm = 8 cm
- AB = 8 cm
- CD = 12 cm

Ditanya : EF = .....?

Penyelesaian :
- EF :

[tex] ef = \frac{ab \times ed + cd \times ae}{ad} \\ ef = \frac{8 \times 5 + 12 \times 3}{8} \\ ef = \frac{40 + 36}{8} \\ ef = \frac{76}{8} \\ ef = 9.5 \: cm[/tex]

Jawaban : A. 9,5 cm

Maaf Kalau Salah