Question

( mathcal{L} )
criven that
[
a=2 i-j+3 k
]
( 8 b=5 i+4 j-2 k )
[
begin{array}{l}
text { Find }|a times b|
(a times b)=left|begin{array}{ccc}
i & j & k
2 & 1 & 3
5 & 4-2
end{array}right|
= & i(-2-12)-j(-4-15)+k(8-5)
& =-14 i+19 j+3 k
end{array}
]
Now
[
begin{aligned}
|(9 x b)| &=sqrt{(-14)^{2}+(9)^{2}+6 x^{2}}
&=sqrt{196+361+9}
&=sqrt{566}
end{aligned}
]

# (b) if a=2i- j +3k and b = 5i +4-2k then find lax b|

Solution