Answer:

Step-by-step explanation:
The parameters of the angle θ₁ are;
The location of θ₁ = Quadrant II
cos(θ₁) = -22/29
We note the following;
1) The sine of an angle in quadrant II is positive
2) The cosine of an angle in quadrant II is negative,
2) The cos of an angle = The adjacent leg length to the reference angle divided by the hypotenuse length of a right triangle
3) With regards to the right triangle for finding cos(θ₁)
The adjacent leg length = -22 (The x-axis is negative in quadrant II)
The hypotenuse length = 29
The negative sign is obtained from the value of cosine in the quadrant
Therefore, by Pythagoras' theorem, for a right triangle, we have;
The opposite leg length to 'θ₁' = √(29² - 22²) = √(357)

Therefore, we have;
.
We need to write system of equations to solve this problem.
we have 3 unknown variables.
a,b,c which are shorter leg, longer leg and hypotenuse.
b = a+6
c+6 = 2*a
c^2 = a^2 + b^2
(2a - 6)^2 = a^2 + (a+6)^2
4a^2 - 24a + 36 = a^2 + a^2 + 12a + 36
2a^2 = 36a
a^2 = 18a
a = 18
b = 24
c = 30
This is the associative property of addition. It states that no matter where you switch the numbers in an equation full of addition symbols, the answer will remain the same.
The phrase can be written as:

therefore the correct choice is the third one.