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Mathematics
Mathematics
Problem
A vector of magnitude
15
15
15
units has direction cosines
l
=
−
2
3
l=-\dfrac{2}{3}
l
=
−
3
2
and
m
=
1
3
m=\dfrac{1}{3}
m
=
3
1
. If it makes an acute angle with the
z
z
z
-axis, which of the following vectors satisfies these conditions? a)
−
10
i
^
+
5
j
^
−
10
k
^
-10\hat{i}+5\hat{j}-10\hat{k}
−
10
i
^
+
5
j
^
−
10
k
^
b)
−
10
i
^
+
10
j
^
+
5
k
^
-10\hat{i}+10\hat{j}+5\hat{k}
−
10
i
^
+
10
j
^
+
5
k
^
c)
−
5
i
^
+
10
j
^
+
10
k
^
-5\hat{i}+10\hat{j}+10\hat{k}
−
5
i
^
+
10
j
^
+
10
k
^
d)
−
10
i
^
+
5
j
^
+
10
k
^
-10\hat{i}+5\hat{j}+10\hat{k}
−
10
i
^
+
5
j
^
+
10
k
^
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