Mk đang cần gấp giúp mk với :333
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Áp dụng tỉ số lượng giác của góc nhọn vào \(\Delta MHP\), ta có:
\(\cos30\text{°}=\dfrac{MH}{8}\Rightarrow MH=8.\cos30\text{°}=4\sqrt{3}\left(cm\right)\)
Mặt khác, \(\text{∠}MNP=90\text{°}-30\text{°}=60\text{°}\)
Áp dụng tí số lượng giác của góc nhọn vào \(\Delta MHN\), ta có:
\(\tan60\text{°}=\dfrac{4\sqrt{3}}{NH}\Rightarrow NH=4\sqrt{3}.\tan60\text{°}=12\left(cm\right)\)
Lời giải:
Xét tam giác $MHP$ vuông tại $H$ thì:
$\frac{MH}{MP}=\sin P=\sin 30^0=\frac{1}{2}$
$\Rightarrow MH=\frac{MP}{2}=4$ (cm)
Theo định lý Pitago:
$HP=\sqrt{MP^2-MH^2}=\sqrt{8^2-4^2}=4\sqrt{3}$
Theo hệ thức lượng trong tam giác vuông:
$MH^2=NH.HP$
$\Leftrightarrow 4^2=4\sqrt{3}.NH$
$\Leftrightarrow NH=\frac{4\sqrt{3}}{3}$ (cm)
R là NaCl
A là Na, X là Cl2
B là NaOH, Y là HCl
C là Na2SO4, Z là BaCl2
\(NaCl-^{đpnc}\rightarrow Na+\dfrac{1}{2}Cl_2\)
\(Na+H_2O\rightarrow NaOH+\dfrac{1}{2}H_2\)
\(Cl_2+H_2-^{as}\rightarrow2HCl\)
\(NaOH+HCl\rightarrow NaCl+H_2O\)
\(2NaOH+H_2SO_4\rightarrow Na_2SO_4+2H_2O\)
\(2HCl+BaO\rightarrow BaCl_2+H_2O\)
\(BaCl_2+Na_2SO_4\rightarrow BaSO_4+2NaCl\)
1 B
2 B
3 C
4 B
5 C
6 C
7 C
8 B
9 D
10 C
11 A
12 A
13 A
14 D
15 B
16 B
17 A
18A
19 C
20 C
1. He went to the dentist because he had a toothache.
2. I didn't take part in volunteer programs because I didn't have enough time.
3. He doesn't want to go and see the film because he's already seen it.
4. She's popular in school because she's honest and polite.
5. She scolded Alex because he didn't complete his hommework.
6. I went home late night because I missed the last bus.
1. He went to the dentist because he had a toothache
2. I didn't take part in volunteer programs because i didn't have enough time
3. He didn't want to go and see the film because he has seen it already
4. She is popular in school because she is honest and polite
5. She scolded Alex because he didn't complete his homework
6. I went home late last night because i missed the last bus