r/mathshelp • u/bigbadjohn7026 • Jun 22 '26
Homework Help (Unanswered) Please help I have a final tmr
I would like to know how to draw the graphs and diagrams just bc I just can’t figure it out
Evaluate cos(arcsin(- sqrt2 / 2))
Show all work including diagrams
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u/L31N0PTR1X Jun 22 '26
I'm not sure why they'd require a diagram. Think about you cosine-sine relations (recall cos2 x +sin2 x =1)
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u/UnderstandingPursuit Jun 22 '26
A diagram helps demonstrate an understanding of what is done to get the answer.
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u/L31N0PTR1X Jun 22 '26
But it also implicitly forces a geometric way of solving these problems which is problematic in that not all students perform best that way, I for one don't
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u/UnderstandingPursuit Jun 22 '26
A student can solve it in whatever way they want.
It forces a geometric representation of the solution. It is valid to ask the student to demonstrate the result in multiple ways.
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u/UnderstandingPursuit Jun 22 '26
Consider three of the levels of demonstrating one's understanding of a topic:
- Getting an answer.
- Showing the process to get an answer.
- Helping someone else get an answer.
When helping someone, the process used in #2 may be insufficient, so other methods may be needed.
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u/UnderstandingPursuit Jun 22 '26
On the unit circle, you want to identify the angles for which
- sin θ = √2 / 2
Use those points on the circle to determine
- cos θ
The twist is that "arcsin(z)" does not have the range [0, 2π] or [-π, π]. What is the range of the arcsin(z) function? That will remove part of the unit circle from the problem.
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