Cosine theorem?

this formula is used in triangles to define either a cosine or the side of the triangle opposite of the cosine's angle

c2=a2+b2-2abcosc

cosc= the cosine of the angle opposite of the c side of the triangle ABC

hence cosc=(a2+b2-c2)/2ab hereby the same is true for cosa where cosa is the cosine of the angle opposite of the a side and for cosb where cosb is the cosine of the angle opposite of the side b in the triangle

Answered by Petar A. Maths tutor

2922 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

What are the two roots for the equation x^2 + 7x + 10 = 0


Solve this set of simultaneous equations: 5x+3=3y 9x+9=6y


ABC and BCD are two attached triangles, attached along line BC. AB = 5.8cm, AC=5.2cm, BD=4.3cm. Angle BDC = 30 degrees, and angle DCB is a right angle. Calculate angle CBA.


A circle has a radius of 4cm. An isosceles triangle has a base of 8 cm and a height of 12 cm. Which shape has the greatest area?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences