IS THE RELATIONSHIP BETWEEN SIDES AND ANGLES IN ANY GIVEN TRIANGLE
THE FORMULA IS:
a 2 = b 2 + c 2 - 2 b c cos(A)
let's say we have a triangle with the side lengths a=10cm b=7cm c=5cm now let's find the largest angle A.
*first step is to set up the formula
a 2 = b 2 + c 2 - 2 b c cos(A)
*then substitute the numbers in, and solve for the largest angle A.
cos (A) = [ 7 2 + 5 2 - 10 2 ] / (2*7*5)
= -13/35
(your calculator will be a big help now)
your answer should be 111.80
so angle A=111.8(rounded to one decimal place)
THINGS TO REMEMBER:
*a,b,c are the side lengths of a triangle .
* A,B,C are the angles.
*the cosine law is often useful when dealing with triangles which are not right angle.
* label your sides and angles so that you don't get confused.
THAT'S WHAT I'VE GOT ON COSINE LAW
SEE YOU GUYS TOMORROW :)
POSTED BY FAVEN.
Labels: cosine law
