Solution 4.3:4b
From Förberedande kurs i matematik 1
(Difference between revisions)
			  			                                                      
		          
			m  (Lösning 4.3:4b moved to Solution 4.3:4b: Robot: moved page)  | 
				|||
| Line 1: | Line 1: | ||
| - | {{  | + | If we once again use the Pythagorean identity we get  | 
| - | <  | + | |
| - | {{  | + | |
| + | <math>\cos ^{2}v+\sin ^{2}v=1\quad \Leftrightarrow \quad \sin v=\pm \sqrt{1-\cos ^{2}v}</math>  | ||
| + | |||
| + | |||
| + | Because the angle v lies between   | ||
| + | <math>0</math>  | ||
| + | and  | ||
| + | <math>\pi </math>,   | ||
| + | <math>\text{sin }v</math>  | ||
| + | is positive (an angle in the first and second quadrants has a positive   | ||
| + | <math>y</math>  | ||
| + | -coordinate) and therefore  | ||
| + | |||
| + | |||
| + | <math>\sin v=+\sqrt{1-\cos ^{2}v}=\sqrt{1-b^{2}}</math>  | ||
Revision as of 11:42, 29 September 2008
If we once again use the Pythagorean identity we get
\displaystyle \cos ^{2}v+\sin ^{2}v=1\quad \Leftrightarrow \quad \sin v=\pm \sqrt{1-\cos ^{2}v}
Because the angle v lies between 
\displaystyle 0
and
\displaystyle \pi , 
\displaystyle \text{sin }v
is positive (an angle in the first and second quadrants has a positive 
\displaystyle y
-coordinate) and therefore
\displaystyle \sin v=+\sqrt{1-\cos ^{2}v}=\sqrt{1-b^{2}}
