Asked by Jennifer

I need help with these kind of problems. We are dealing with word problems and/or pictures that are solved by the Law of Sin or Cosine. If any one kows a wonderful web site that can help with these, I would greatly appreciate it.
A parollelogram has side lengths 3 and 5, and one angle is 50 degrees. Find the lengths of the diagonals.

Answers

Answered by Reiny
Shorter diagonal: the angle between sides 3 and 5 is 50º (SD for short diagonal)

SD^2 = 5^2 + 3^2 - 2(5)(3)cos 50º

take it from there.

Let me know what you get for the equation of the longer diagonal.
Answered by Jennifer
I got 3.8, we round to the nearest tenths.
Answered by Jennifer
3.8 was my answer for the short diagonal.
I'm not sure how to find the long diagonal.
Answered by Reiny
for the longer, same sides except the angle between them is now 130º

LD^2 = 5^2 + 3^2 - 2(3)(5)cos130
= 25 + 9 - 30(-.642788)
= 7.2996
= 7.3

Notice this time the last term was actually added because of the double negatives.
Answered by Reiny
last two lines should have been

LD = 7.2996
= 7.3

(I still had it equal to LD^2)
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