This shows you the differences between two versions of the page.
| Both sides previous revision Previous revision Next revision | Previous revision Next revision Both sides next revision | ||
|
en:proof-of-the-law-of-cosines [2017/04/12 13:13] federico [Proof] |
en:proof-of-the-law-of-cosines [2017/07/14 10:36] federico |
||
|---|---|---|---|
| Line 7: | Line 7: | ||
| ===== Proof ===== | ===== Proof ===== | ||
| - | If divide the triangle into 2 right angle triangles: | + | Divide the triangle into 2 right angle triangles: |
| - | image-2 | + | {{:en:law-of-cosines2-fs8.png?nolink|}} |
| Using trigonometry, the sides of the green triangle are | Using trigonometry, the sides of the green triangle are | ||
| Line 15: | Line 15: | ||
| * (b sin θ) | * (b sin θ) | ||
| * (c - b cos(θ)) | * (c - b cos(θ)) | ||
| + | |||
| + | {{:en:law-of-cosines3-fs8.png?nolink|}} | ||
| Using the Pythagorean Theorem: | Using the Pythagorean Theorem: | ||