Answer:
x = [tex]\sqrt{21}[/tex]
Step-by-step explanation:
AC² = AB² + BC²
BC² = 3² + x² = 9 + x²
AB² = 7² + x² = 49 + x²
But AC² = (7 + 3)² = 100
∴ 100 = 49 + x² + 9 + x²
2x² + 58 = 100
x² = 50 - 29 = 21
Answer: the answer is the square root of 21.
What I did was I just multiplied 7 times 3 and got 21 and that was the answer.
