Better Students Ask More Questions.
Whic are the two values of side AC for the triangle ABC with AB=9 cm, BC= 7cm and...
1 Answer | add yours
We'll apply cosine theorem, since we know the measure of an angle and the lengths of 2 sides:
BC^2 = AB^2 + AC^2 - 2AB*AC*cos 40
We'll substitute the values of the lengths known:
7^2 = 9^2 + AC^2 - 2*9*AC*cos 40
49 = 81 + + AC^2 - 13.78*AC
We'll get the quadratic:
AC^2 - 13.78*AC + 32 = 0
We'll apply quadratic formula:
AC = [13.78+sqrt(189.8884-128)]/2
AC = (13.78+7.86)/2
AC = 10.82 cm
AC = (13.78-7.86)/2
AC = 2.96 cm
The 2 values of the lengths of the side AC are: AC=10.82 cm and AC = 2.96 cm.
Posted by giorgiana1976 on April 4, 2011 at 11:06 PM (Answer #1)
Join to answer this question
Join a community of thousands of dedicated teachers and students.