Từ câu 16 đến câu 20.
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12. điền vào chỗ ... chữ "by"
13. were used
14. was opened
15. is visited by
16. is known
\(0< a< \dfrac{\pi}{2}\Rightarrow cosa>0\)
\(\Rightarrow cosa=\sqrt{1-sin^2a}=\sqrt{\dfrac{2}{3}}\)
\(cos\left(a+\dfrac{\pi}{3}\right)=cosa.cos\left(\dfrac{\pi}{3}\right)-sina.sin\left(\dfrac{\pi}{3}\right)=\dfrac{\sqrt{6}-3}{6}\)
20.
Đề bài sai, do \(\dfrac{3\pi}{2}>\pi\) nên không thể tồn tại góc a sao cho \(\dfrac{3\pi}{2}< a< \pi\) được
Câu 1:
uses crt;
var i,t:integer;
begin
clrscr;
t:=0;
for i:=1 to 20 do
if i mod 4=0 then t:=t+i;
writeln(t);
readln;
end.
Câu 2:
uses crt;
var i,dem:integer;
begin
clrscr;
dem:=0;
for i:=1 to 20 do
if i mod 3=0 then dem:=dem+1;
writeln(dem);
readln;
end.
Tất cả những câu mình viết bạn chỉ cần thêm in spite of hoặc despite vào đầu câu nhé (tự chọn)
1 the wide river, we can swim across it
2 the high celling, they can reach it
3 being very poor, Ba continued to go to school
4 being short, Tuan couldn't asleep in this sleeping bag
5 being careful, the children broke the vase
6 being tall, Nam can't play volleyball
7 being ill, my mother must go to work
8 being tired, Hanh went to school
9 his friendliness, I don't love him
10 being sick, she went to bed late
11 being careful, Phong always gets bad marks
12 being rich, my father is always economical
13 Miss Linh's beauty,my brother doesn't like her
14 being old, my grandmother can lift that box
15 their difficulty, we can do these exercise
16 this table's lightness, hoa can't lift it
17 this yarrd's hugeness, we don't want to play in it
18 the river's danger, we often swim in it
19 being young, I often drive a car
20 the yard's smallness, we can play soccer in it happily
18.
\(-x^2+2x-5\le0\) có \(\left\{{}\begin{matrix}a=-1< 0\\\Delta'=1-5=-4< 0\end{matrix}\right.\)
\(\Rightarrow-x^2+2x-5\le0\) ; \(\forall x\in R\)
19.
Thay tọa độ lần lượt các đáp án lên thì chỉ D đúng
20.
Chu vi đường tròn: \(2\pi R=40\pi\left(cm\right)\)
Số đo của cung: \(\dfrac{35.2\pi}{40\pi}=\dfrac{7}{4}\)