Figure 3.6.2 shows an acute triangle with angles A, B, and C and opposite sides a, b,

Question:

Figure 3.6.2 shows an acute triangle with angles A, B, and C and opposite sides a, b, and c. By dropping a perpendicular from each vertex to the opposite side, derive the equations


image


Regarding these as linear equations in the unknowns cosA, cosB, and cosC, use Cramer’s rule to derive the law of cosines by solving for


image


Thus


a2 = b2 + c2 - 2bc cosA.


Note that the case A = π/2 (90°) reduces to the Pythagorean theorem.


image

Fantastic news! We've Found the answer you've been seeking!

Step by Step Answer:

Related Book For  answer-question

Differential Equations And Linear Algebra

ISBN: 9780134497181

4th Edition

Authors: C. Edwards, David Penney, David Calvis

Question Posted: