X = = (-275)
11. 如圖,△ABC中,AD垂直 BC,已知AB=25,sinB = 5
10.已知為銳角,且滿足方程式2sin²+3sin = 2,則tan² 的值為
3½ sino = x
=>2X²+3X-2=0
= (x-1) (x+2) = 0
字。
tan² 0 = 3
=> sing = 600
105
12
=-
,
sin C=
=-
,
則BC =
4
A
13
AD =
>5 x 3/3 = 15
CD
25.
K
15
12
AC =
x =
13
B
C
20
D
65
X =
=>
216
12.已知為銳角,且sin+cose=-
sint @ + 2 sin@cose + cos² 0.
Bing cos8=
12
7
5
49
,
13.為銳角,若2sin-cos=1,則cose =
則sin-cos=土豆
4225
16
625
-
132
3600
25
4
16
=> BC
siño - 2 coso sino + cos² 0 = 1 - 2 × 1/3
65.2
:
20 +
=
105
4
==> (sino - Coso) =
15
sine co
3
5
(3sino) = (40056)²