Question

Find the equation of the tangent to the curve y = cosπx at the point when x = ½

Answer 1

You need a point....first do that by plugging in x = ½ to y = cosπx
(½,y) where y is whatever you find

Afterwards you need a slope....you do that by finding the derivative of
cosπx and plugging in x = ½

After that you use

y-y1=m(x-x1)

where (x1,y1) is the point you got and m is the slope

Answer 2

Yeah, I've done that.

I got:
y = cosπ/2
m = -πsinπx

y - cosπ/2 = -πsinπ/2(x - ½)
2y - cosπ = -πsinπ(x - ½)
2y - cosπ = -πxsinπ + (πsinπ)/2
4y - 2cosπ = -2πxsinπ + πsinπ
2πxsinπ + 4y - πsinπ - 2cosπ = 0

I think I'm wrong, I feel i did it wrong... help haha.

Answer 3

Looking at the first part it seems like you did it right but I'll get someone else to check....I think it looks right

Answer 4

@ParthKohli

Answer 5

i guess you were right