A triangle has sides a,b,c and angles A,B,C with a opposite A etc. If a=4,b=3,A=40, what is the area of the triangle?

First use the sine rule (that a/sin(A)=b/sin(B)=c/sin(C)) to find the value of B. a/sin(A)=b/sin(B) so B=arcsin(bsin(A)/a) which is approximately equal to 28.82. Since the angles of a triangle have 180 degrees we then know that C is roughly equal to 111.18. Now we can use S=ab*sin(C)/2 where S is the area of the triangle so the area is roughly 5.59.

Answered by Maths tutor

2476 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

The line AB has equation 5x + 3y + 3 = 0 and it intersects the line with equation 3x - 2y + 17 = 0 at the point B. Find the coordinates of B.


Integrate xcos(x)


What is a derivative?


Express 9^(3x+1) in the form 3^y, giving "y" in the form "ax+b" where "a" and "b" are constants.


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences