An acute triangle has sides measuring 10 cm and 16 cm. the length of the third is unknown. which is best describes the range of the possible values for the third side of the triangle? x< 12.5'x> 18.9 12.5 6

6 < x < 18.9

Justification

1) An acute angle is less than 90° and greater that 0°, i.e. 0 < angle < 90°.

2) The lower bound of the third side is when the angle approaches to zero, this is both sides 10 and 16 almost overlap.

Under this condition the lenght of the third side approaches (never gets to) 16 - 10 = 6.

From this you conclude x > 6.

3) The upper bound of the third side is when the angle approaches 90°, this is the triangle is almost a right triangle. In this case, the upper limit of x is the value of the hypotenuse of a triangle withs legs 10 and 16.

=> x^2 < 10^2 + 16^2

=> x^2 < 100 + 256

=> x^ 2 < 356

=> x < 18.86

So the range is 6 < x < 18.86