Cos (B) = (a^2 + c^2 -b^2) / (2 * a * c)
cos (B) = (11^2 +17^2 -12^2) / (2 * 11 * 17)
cos (B) = (121 + 289 -144) / (374)
cos (B) = 266 / 374
cos (B) =
<span>
<span>
<span>
0.7112299465
Angle B = </span></span></span>44.665 degrees
Option 1! If you expand the bracket and simplify.
Answer:
Step-by-step explanation:
Eq. 1 ) −5x−3y−9=0
Eq. 2) 4x−18y−54=0
there are two routes to solve this, Substitution or elimination, I'll go for the 2nd one because I can see that the y values are a multiple of each other :)
6 *( −5x−3y−9=0 )
Eq. 3) -30x -18y =54
subtract Eq. 2 from Eq. 3 :)
-30x -18y =54
<u>-( 4x−18y=54)</u>
-34x = 0
so according to the equations then x =0 but, that's not really a full answer, so now we should go back and try the other method, substitution,
then:
-5x = 9 +3y
x = - 9/5 + (-3/5)y
now plug that into Eq. 2
4( - 9/5 + (-3/5)y ) - 18y = 54
-36/5 + (-12/5)y -18y = 54
(-12/5)y - (90/5)y = 54+36/5
-(102/5)*y =270/5+36/5
-(102/5)y = 306/5
y = (-5/102)*(306/5)
y = -306/102
y = -3
then plug in for either equation
-5x-3( -3) = 9
-5x + 9 = 9
-5x = 0
x = 0
now we have the full answer
check it by plugging in both x and y into the 2nd equation
4(0) - 18(-3) = 54
54= 54
this seems good
The answer is C 84. Your welcome
B.4
1/4 divided by 2
do the reciprocal
1/4 times 1/2=2/8
divide 8by 2
