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roberts61 · Apr 27, 2009, 11:38 PM

again I've hit a brick wall with my (none) calculations, I can't figure out how to get from 1 point to the next

x = 4cos15 y = - 4sin15 = 4 x 0.966 = - 4 x 0.259
= 3.864N = - 1.036N

it may seem easy for some, but I just can't get from the red to the answer, even thought the answer is given

regards
Peter

Unknown008 · Apr 28, 2009, 01:41 AM

Huh? What exactly is the question? Is it finding the value of x and of y? Your calculator should give you the right answers just by pressing 4cos15 and -4sin15...

roberts61 · Apr 28, 2009, 04:51 AM

Originally Posted by Unknown008

Huh? what exactly is the question? Is it finding the value of x and of y? Your calculator should give you the right answers just by pressing 4cos15 and -4sin15...

I apologise if I didn't come across too clear, this trigonometry's doing my head in at the moment, at 47 I think I've forgot a lot of the basics :confused:

ebaines · Apr 28, 2009, 05:44 AM

Hello Roberts61. It sounds like you are trying to plot the (x,y) coordinates of a point on a graph, where:

x = 4 cos(15) = 4*.966 = 3.86
y = -4 sin(15) = -4 * .259 = -1.03

These are the copordinates of point on a circle of radius 4 that is 15 degrees clockwise from the horizontal axis. Does that make sense?