中二數學共三題10分

1)求這一題的圖= =

2)a) QR^2 SR^2
= 144 cm^2 25 cm^2
= 169 cm^2
= ( 13 cm )^2
= QS ^2
所以,∠QRS=90°(畢氏定理逆定理)
所以SR⊥RQ

b)因為S點平分PR
所以PR=2SR
=10cm
因為∠QRP=90°
所以 PQ^2 = PR^2 QR^2 (畢氏定理)
= 100 cm^2 144 cm^2
PQ = 15.62 cm

c) sin∠C = AB / AC
AB = 12 cm * sin60°
AB = 10.39cm(準確至兩位小數)
cos∠C = BC / AC
BC = 12cm * cos60°
BC = 12cm * 0.5
BC = 6cm
三角形面積=AB*BC/2
=31.18 cm^2(準確至兩位小數)