Obviously it's answer D) Why?
a) any side of a triangle is SMALLER than the SUM of the 2 others
b) any side of a triangle is GREATER than the DIFFERENCE of the 2 others
Hence D) 8-5 < QS < 8+5==>3 < QS < 13
Sn = a1 * (1 - r^n)
----------
1 - r
n = 5 so answer =
1 * (1 - (1/2)^5
--------------- = 31/16
1 - 1/2
The sum of the interior angles of a triangle is 180 degrees.
1.) Translating the problem into equation:
7:11:12 = 180 degrees
7x+11x+12x = 180 degrees; Where x = missing number
30x = 180
30x/30 = 180/30 divide both sides by 30
x = 6
2.) Substitute the values:
7x+11x+12x = 180
7(6)+11(6)+12(6) = 180
42+66+72 = 180
180 = 180
3.) Therefore, the angles should be 42 degrees, 66 degrees and 72 degrees.
4.) See attached drawing of triangle
The simplified equation of
is 
<h3>How to determine the simplified equation?</h3>
The complete question is added as an attachment
The equation is given as

Subtract (x - 10)^2 from both sides

Evaluate 4^2

Take the square root of both sides

Add 6 to both sides

Hence, the simplified equation of
is 
Read more about simplified equation at:
brainly.com/question/723406
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