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Can someone help me with this question?

Can someone help me with this question?-example-1
User Baumann
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1 Answer

6 votes

Answer:

Explanation:

Compare both shapes

Find out the length of the red line through Pythagoras theorem

a² + b² = c²

9² + b² = 15²

15²- 9² = b²

144 = b²

√144 = b

b = 12

Red line is 12 and the other length of one side of the triangle is x - 9

The hypotenuse of the other triangle will be equal to:

a² + b² = c²

12² + (x-9)² = c²

144 + x² - 9x -9x + 81 = c²

x² - 18x + 225 = c²

THE HYPOTENUSE OF THE 2ND TRIANGLE = x² - 18x + 225

NOW COMPARE BOTH TRIANGLES

x² - 18x + 225 : 15

x - 9 : 9

Cross multiply

9(x² - 18x + 225) = 15(x - 9)

9x² - 162x + 2025 = 15x - 135

9x² - 162x - 15x + 2025 + 135 = 0

9x² - 177x + 2160 = 0

Now use the quadratic equation

x = (-b +- √b² - 4ac)/2a

a = 9

b = -177

c = 2160

x = (-(-177) +- √(-177)² - 4(9)(2160))/(2×9)

x = (177 +- √31329 - 77760)/(18)

x = (177 +- √-46431)/18

At this point I have lost hope in the question as i got a negative value under square root which means it can't be solved.
I don't know where I am wrong but I hope the starting parts of the answer help you reach the final answer.

User Amet Alvirde
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3.8k points