A kite with diagonals is shown. It has side lengths of 13, 13, 37, and 37. The length from the left point to the middle point is 12, and the distance from the right point to the middle point is 12. The figure is a kite. What is the length of the kite’s longer diagonal?

5 units
35 units
40 units
48 units

Step-by-step explanation:

we have to solve 2 right-angled triangles via Pythagoras

c² = a² + b²

with c being the Hypotenuse (the side opposite of the 90° angle).

one triangle is 37, 12 and the longer part of the long diagonal.

the second triangle is 13, 12 and the shorter part of the long diagonal.

the whole diagonal is then the sum of both parts.

37² = 12² + longer part²

1369 = 144 + longer part²

longer part² = 1225

longer part = 35

13² = 12² + short part²

169 = 144 + short part²

25 = short part²

short part = 5

so, the total diagonal is 35 + 5 = 40 units.

starting with:    

5 + x - 12 = 2x - 7   

5 + x - 12 - x = 2x - 7 - x (subtract x from both sides)   

5 - 12 = x - 7 (combine and cancel x's from both sides)   

5 - 12 + 7 = x - 7 + 7 (add 7 to both sides)   

0 = x (add numbers together on both sides)       

so in order for the equation to be true, x must be 0.   

trying x = -0.5   

5 + x - 12 = 2x - 7 (original equation)   

5 + -0.5 - 12 = 2(-0.5) - 7 (plug in value of x)   

5 + -0.5 - 12 = -1 - 7 (did multiplication)   

-7.5 = -8 (did addition on both sides)       

since -7.5 is obviously not equal to -8, the value of -0.5 for x is wrong.   

trying x = 0   

5 + x - 12 = 2x - 7 (original equation)   

5 + 0 - 12 = 2(0) - 7 (plug in value of x)   

5 + 0 - 12 = 0 - 7 (did multiplication)   

-7 = -7 (did addition on both sides)       

since -7 equals -7, that demonstrates that the value of 0 for x is correct.   

trying x = 1   

5 + x - 12 = 2x - 7 (original equation)   

5 + 1 - 12 = 2(1) - 7 (plug in value of x)   

5 + 1 - 12 = 2 - 7 (did multiplication)   

-6 = -5 (did addition on both sides)       

since -6 is obviously not equal to -5, the value of 1 for x is wrong.