Trig proof q (1 Viewer)

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[ExtremelyBoredUser]

View attachment 36778

man this shit be giving me ptsd to MX1 2022 q1 mc.

ok let b = theta

Consider cosx - cos(x+2b):
Let A = x+b, B = b
2sin(x+b)sinb = cos(x) - cos(x+2b) as required


Ok now consider LHS:
= 2sin(x+b)sin(b)/2sin(b)
= sin(x+b)
= RHS

If only MX1 had these typa questions all goods ima cope here

 

[chilli 412]

is that meant to say 2theta instead of 20?

 

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I’m not sure might be a typo thanks anyway