- #1

chwala

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- Homework Statement
- See attached;

- Relevant Equations
- sine and cosine angle rules

This is clear to me; i just wanted to know in which contexts is one allowed to use one rule over the other; or it does not matter.

The angle i realise can also be found by;

##\sin θ = \dfrac{||v×w||}{||v||||w||}##= ##\dfrac{||-3i-5j-11k||}{\sqrt{6}\sqrt{26}}##=##\dfrac{\sqrt{155}}{\sqrt{6}\sqrt{26}}=0.99679## to 5 decimal places...

##⇒θ=\sin^{-1} [0.99679]= 85.41^0##

In which contexts is one allowed to use sine angle rule? ; or is it dependant on the question as directed? cheers...

The angle i realise can also be found by;

##\sin θ = \dfrac{||v×w||}{||v||||w||}##= ##\dfrac{||-3i-5j-11k||}{\sqrt{6}\sqrt{26}}##=##\dfrac{\sqrt{155}}{\sqrt{6}\sqrt{26}}=0.99679## to 5 decimal places...

##⇒θ=\sin^{-1} [0.99679]= 85.41^0##

In which contexts is one allowed to use sine angle rule? ; or is it dependant on the question as directed? cheers...

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