Each answer box is worth 1 point a 54 b 41 c 15 A B C a 3
Each answer box is worth 1 point. a =5.4 b =4.1 c =1.5 A = B = C = a =3.6 b =9.7 C =37.5degree A = B = c = a =1.9 b =5.9 c =6.2 A = B = C =
Solution
1. a= 5.4 ; b= 4.1 c = 1.5
Use cosine rule : a^2 = b^2 +c^2 -2bccosA
substituitng the values of a,b,c find A
cosA = ( 4.1^2 +1.5^2 -5.4^2)/2*4.1*1.5
A = 145.2 deg
Use agian cosine rule to fing angle C:
cosC = (a^2 +b^2 -c^2)/2ab
C= 9.12 deg
So, angle B = 180 -A - C = 25.68 deg
2. a = 7.2
B = 106.7
C = 39.4
So , angle A = 180 - B -C = 180- 106.7 -39.4 = 33.9 deg
Use sine rule:
a/sinA = b/sinB
b = a*sinB/sinA = 7.2*sin106.7/sin39.4 = 10.86
Again use sine rule to find c:
a/sinA = c/sinC
c = a*sinC/sinA = 7.2*sin106.7/sin37.5 = 11.33
