1.68 mm per year for 1.5 years could be rewritten as
(2.00-0.32) mm per year for 1.5 yrs.
Multiply: (1.5 yrs)(2.00-0.32)(mm/yr) = 3 mm + 0.48 mm = 3.48 mm
This approach makes use of the distributive property of multiplication.
Recall the angle sum identities:
cos(a + b) = cos(a) cos(b) - sin(a) sin(b)
cos(a - b) = cos(a) cos(b) + sin(a) sin(b)
sin(a + b) = sin(a) cos(b) + sin(b) cos(a)
sin(a - b) = sin(a) cos(b) - sin(b) cos(a)
Notice that adding the first two together, and subtract the last from the third, we get two more identities:
cos(a + b) + cos(a - b) = 2 cos(a) cos(b)
sin(a + b) + sin(a - b) = 2 sin(b) cos(a)
Let a = 4x and b = x. Then
cos(5x) + cos(3x) = 2 cos(4x) cos(x)
sin(5x) - sin(3x) = 2 sin(x) cos(4x)
Now,

as required.
Hi Kristian
a - 3b = 22
a = b - 2
We need to solve a = b -2 for a
First, we need to substitute b - 2 for a in a - 3b = 22
a - 3b = 22
b - 2 - 3b = 22
-2b - 2 = 22
-2b = 22 + 2
-2b = 24
b = 24/-2
b = -12
Now substitute -12 for b in a = b - 2
a = b -2
a= -12 - 2
a= -14
Thus, the solution is a = -14 and b = -12
The correct option is the last one (-14,-12)
If you have questions about my answer, please let me know.
Good luck!
Answer:
yes, but the answer will be a decimal. the answer is 16.5.
Step-by-step explanation: