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 !
Answer:
no. 4
Step-by-step explanation:
the numbers start at two and keeps going up.
Just add them
QM+MR=QR
16+x+2(x+2)=QR
16+x+2x+4=QR
20+3x=QR
Answer:
Rate of interest r = 2.83 % (Approx.)
Step-by-step explanation:
Given:
Amount invested p = $2,600
Amount get A = $4,300
Number of year n = 18
Find:
Rate of interest r
Computation:
A = p(1+r)ⁿ
4,300 = 2,600(1+r)¹⁸
(1+r)¹⁸ = 1.653846
Rate of interest r = 2.83 % (Approx.)
The wording of the question kinda doesn't make sense in some parts, but I'll try anyway. 1 plus 4 is 5, and since BC is 5, x is 1 for BC. -3 plus 14 is 11, so x is -3 for AB.
