As soon as I read this, the words "law of cosines" popped
into my head. I don't have a good intuitive feeling for the
law of cosines, but I went and looked it up (you probably
could have done that), and I found that it's exactly what
you need for this problem.
The "law of cosines" relates the lengths of the sides of any
triangle to the cosine of one of its angles ... just what we need,
since we know all the sides, and we want to find one of the angles.
To find angle-B, the law of cosines says
b² = a² + c² - 2 a c cosine(B)
B = angle-B
b = the side opposite angle-B = 1.4
a, c = the other 2 sides = 1 and 1.9
(1.4)² = (1)² + (1.9)² - (2 x 1 x 1.9) cos(B)
1.96 = (1) + (3.61) - (3.8) cos(B)
Add 3.8 cos(B) from each side:
1.96 + 3.8 cos(B) = 4.61
Subtract 1.96 from each side:
3.8 cos(B) = 2.65
Divide each side by 3.8 :
cos(B) = 0.69737 (rounded)
Whipping out the
trusty calculator:
B = the angle whose cosine is 0.69737
= 45.784° .
Now, for the first time, I'll take a deep breath, then hold it
while I look back at the question and see whether this is
anywhere near one of the choices ...
By gosh ! Choice 'B' is 45.8° ! yay !
I'll bet that's it !
Hey there!
y = -2x + 19
y = x + 7
We gonna solve this system of equation by using the substitution method.
We wanna solve y = -2x + 19 for y
Let start by substitute -2x + 19 for y in y = x + 7
y = x + 7
-2x + 19 = x + 7
Subtract x from both sides
-2x + 19 - x = x + 7 - x
-3x + 19 = 7
Now subtract 19 on both sides
-3x + 19 - 19 = 7 - 19
-3x = -12
Then divide both sides by -3
-3x/-3 = -12/-3
x = 4
We have the value of x. Now we gonna use that same value to find the value for y.
We gonna do that by substitute 4 for x in y = -2x + 19
y = -2x + 19
y = -2(4) + 19
y = -8 + 19
y = 11
Thus,
The answer is: x = 4 and y = 11
Let me know if you have questions about the answer. As always, it is my pleasure to help students like you!
Answer:
24
Step-by-step explanation:
9+6(2+3/6)
9+6(2+1/2)
2+1/2 = 2.5
9+6(2.5)
9+15
24
What is - 4/5 times -5/7?
20/35 or in simplified form 4/7
