鍗曞厓绱犲吇璇勪环
(
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)
(
绗叚绔?/p>
)
(120
鍒嗛挓
150
鍒?/p>
)
涓�銆佸崟椤归�夋嫨棰?/p>
(
鏈ぇ棰樺叡
10
灏忛锛屾瘡灏忛
4
鍒嗭紝鍏?/p>
40
鍒?/p>
.
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)
1.(2019
路榫欏博楂樹簩妫�娴?/p>
)
鍦ㄢ柍
ABC
涓紝A=60掳锛孊=75掳锛?/p>
a=10
锛屽垯
c
绛変簬
(
)
A.5
B.10
C.
D.5
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C.
鍥犱负
A=60
掳锛?/p>
B=75
掳锛?/p>
鎵�浠?/p>
C=180
掳
-A-B=45
掳锛屾墍浠ョ敱姝ｅ鸡瀹氱悊鐭?/p>
c=
=
=
.
銆愬姞缁兟峰浐銆?/p>
鈻?/p>
ABC
鐨勫唴瑙?/p>
A
锛?/p>
B
锛?/p>
C
鐨勫杈瑰垎鍒ヤ负
a
锛?/p>
b
锛?/p>
c
锛屽凡鐭?/p>
a=
锛?/p>
c=2
锛?/p>
cos A=
锛屽垯
b=
(
)
A.
B.
C.2
D.3
銆愯В鏋愩�戦�?/p>
D.
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4+b
2
-2
脳
2bcos A=5
锛?/p>
鏁寸悊寰?/p>
3b
2
-8b-3=0
锛?/p>
瑙ｅ緱
b=3
鎴?/p>
b=-
(
鑸?/p>
)
2.
璁?/p>
x
锛?/p>
y
鈭?/p>
R
锛屽悜閲?/p>
a
=(x
锛?/p>
1)
锛?/p>
b
=(1
锛?/p>
y)
锛?/p>
c
=(2
锛?/p>
-4)
锛屼笖
a
鈯?/p>
c
锛?/p>
b
鈭?/p>
c
锛屽垯
|
a
+
b
|=
(
)
A.
B.
C.2
D.10
銆愯В鏋愩�戦�?/p>
B.
鐢?/p>
a
鈯?/p>
c
寰?/p>
a
路
c
=2x-4=0
锛屾墍浠?/p>
x=2
锛?/p>
鐢?/p>
b
鈭?/p>
c
寰?/p>
1
脳
(-4)=2y
锛屾墍浠?/p>
y=-2
锛?/p>