Solution 4.3:3e
From Förberedande kurs i matematik 1
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| - | {{  | + | The angle   | 
| - | <  | + | <math>\frac{\pi }{2}+v</math>  | 
| - | {{  | + | makes the same angle with the positive   | 
| + | <math>y</math>  | ||
| + | -axis as the angle   | ||
| + | <math>v</math>  | ||
| + | makes with the positive   | ||
| + | <math>x</math>  | ||
| + | -axis, and hence we see that the   | ||
| + | <math>x</math>  | ||
| + | -coordinate for   | ||
| + | <math>\frac{\pi }{2}+v</math>  | ||
| + | is equal to the   | ||
| + | <math>y</math>  | ||
| + | -coordinate for   | ||
| + | <math>v</math>, but with a change of sign, i.e.  | ||
| + | |||
| + | |||
| + | <math>\cos \left( \frac{\pi }{2}+v \right)=-\sin v=-a</math>  | ||
[[Image:4_3_3_e-1.gif|center]][[Image:4_3_3_e-2.gif|center]]  | [[Image:4_3_3_e-1.gif|center]][[Image:4_3_3_e-2.gif|center]]  | ||
| + | |||
| + | |||
| + | angle   | ||
| + | <math>v</math>  | ||
| + | angle    | ||
| + | <math>\frac{\pi }{2}+v</math>  | ||
Revision as of 09:12, 10 October 2008
The angle \displaystyle \frac{\pi }{2}+v makes the same angle with the positive \displaystyle y -axis as the angle \displaystyle v makes with the positive \displaystyle x -axis, and hence we see that the \displaystyle x -coordinate for \displaystyle \frac{\pi }{2}+v is equal to the \displaystyle y -coordinate for \displaystyle v, but with a change of sign, i.e.
\displaystyle \cos \left( \frac{\pi }{2}+v \right)=-\sin v=-a
angle 
\displaystyle v
angle  
\displaystyle \frac{\pi }{2}+v


