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Could someone please explain to me the following C3 level question? I would really appreciate any help as I am completely stuck at the moment.

Given that y = arccos x, -1 <= x <= 1 and 0 <= y <= pi,

(a) express arcsin x in terms of y.

I have written down that x = cos y but I do not know where to go from here. It says on the markscheme that:

x = sin (pi/2 - y) which leads to arcsin x = pi/2 - y

arcsinx = arcsin cos y

but I do not understand why this is the case. Could someone please help with this and part (b) of the question also?

(b) Hence evaluate arccos x + arcsin x. Give your answer in terms of pi.

Thank you.

Cathy

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# Homework Help: C3 help

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