need help with triangles trig
A triangle has 3 sides. 4.2, 5.3, 7.6. Calculate the size of the largest angle of the triangle (1 d.p) I know that the Cosine rule is used but I don't know how to work it out. The formula I used to try and solve this was "Cos C=a (squared)+b(squared) - c (squared) then divided by 2ab in order to find the angle. Please could someone help me because I've seen people do the cosine formula for side. Please could someone help me ASAP. Thank you
In every triangle the largest side is opposite the largest angle. In this case the largest angle is the angle opposite the side with length 7.6.
7.62 = 4.22+5.32 – 2 x 4.2 x 5.3 x Cos(A)
Cos(A) = (4.22+5.32 _ 7.62) / 2 x 4.2 x 5.3
Cos(A) = - 0.27…
A = Cos-1 -0.27…= 105.68
7.62 = 4.22+5.32 – 2 x 4.2 x 5.3 x Cos(A)
Cos(A) = (4.22+5.32 _ 7.62) / 2 x 4.2 x 5.3
Cos(A) = - 0.27…
A = Cos-1 -0.27…= 105.68
Original post by IXxi HIIDA ixXI
In every triangle the largest side is opposite the largest angle. In this case the largest angle is the angle opposite the side with length 7.6.
7.62 = 4.22+5.32 – 2 x 4.2 x 5.3 x Cos(A)
Cos(A) = (4.22+5.32 _ 7.62) / 2 x 4.2 x 5.3
Cos(A) = - 0.27…
A = Cos-1 -0.27…= 105.68
7.62 = 4.22+5.32 – 2 x 4.2 x 5.3 x Cos(A)
Cos(A) = (4.22+5.32 _ 7.62) / 2 x 4.2 x 5.3
Cos(A) = - 0.27…
A = Cos-1 -0.27…= 105.68
Thank you so much for your answer
Quick Reply
Related discussions
- Similar shapes question
- Maths Question
- Struggling with Year 2 pure maths
- Help urgently maths
- Maths trig question
- What topics are NOT in the non calculator paper in GCSE maths?
- Cuboid questionpaper1highermathsedecell
- Astrophysics diffraction question
- Sine and cosine rule
- AL Maths Question-need some help!
- Resultant Forces A Level Mechanics Help
- Help urgent mechanics
- Further maths: Further Calculus
- hard gcse vectors question
- alevel mechanics moments help
- Maths trig
- Changing Perspective
- Help with complex summation further maths a levels
- Tips for drawing components of forces in A-level Maths mechanics
- GCSE Edexcel Maths - trigonometric ratios of angles between 0 and 360
Latest
Trending
Last reply 3 days ago
Did Cambridge maths students find maths and further maths a level very easy?Last reply 2 weeks ago
Edexcel A Level Mathematics Paper 2 unofficial mark scheme correct me if wrongMaths
71
Trending
Last reply 3 days ago
Did Cambridge maths students find maths and further maths a level very easy?Last reply 2 weeks ago
Edexcel A Level Mathematics Paper 2 unofficial mark scheme correct me if wrongMaths
71
