Question

sally

想問一下星號的部分是怎麼得到的🙏

1
3'
1. A ABC+, AB=4, AC=3, cos A= AD 為∠A的角平分線段,
如右圖,試求
RAD.XXXXing + = x3x + sine = x +420
Sinze - 24ing 1040
2x sing
= 12 Simbiose
B
4
D

類題演練 1.
【解析】
1.
8√6
7
2
AD=x,
HAABC=A ABD + AACD
= -1/- X4X3 X sin 20
2
=>x=
2.
= 24
BAD= CAD= 0.
√√3+1
3
X4xxx sin 0 +
x 3xxx sin 0,
sin 20 = 2 sin cos
7
⇒12 sin cos 0 = Xxx sin
2
cos 0 =
24
7
1+ cos 20
2
2
= 24×√ √²-8√/6
7
3
7
B
1
A
100
x
D
3
C