Answer: choice B) 19.1 inches
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Explanation:
The TV is a rectangle. Cut the rectangle into two triangles along the diagonal of the rectangle. Focus on only one of the triangles. This triangle is a right triangle.
Since we have a right triangle, we can use the pythagorean theorem
a = 34 is the width
b = x is the unknown height
c = 39 is the diagonal
'a' and 'b' are the legs of the right triangle
c is the hypotenuse
Plug those values into the pythagorean theorem to solve for x
a^2+b^2 = c^2
34^2+x^2 = 39^2
1156+x^2 = 1521
1156+x^2-1156 = 1521-1156
x^2 = 365
sqrt(x^2) = sqrt(365)
x = sqrt(365)
x = 19.1049731745428
which rounds to 19.1
