Answer:
- AB = 7 cm
Step-by-step explanation:
<u>Use the law of cosines to find the side AB:</u>
<u>Use the Heron's area formula next:</u>
, where s- semi perimeter
- s = 1/2[x + x + 3 +
) = 1/2 (2x + 3 +
- s - a = 1/2 (2x + 3 +
- 3)
- s - b = 1/2 (2x + 3 +
- s - c = 1/2 (2x + 3 +
<u>Now</u>
- (s - a)(s - b) = 1/4 [(x²+3x+9) - 9] = 1/4 (x² + 3x)
- s(s - c) = 1/4 [(2x + 3)² - (x² + 3x + 9)] = 1/4 (3x²+ 9x) = 3/4(x² + 3x)
<u>Next</u>
- A² = 3/16(x² + 3x)(x² + 3x)
- 300 = 3/16(x² + 3x)²
- 1600 = (x² + 3x)²
- x² + 3x = 40
<u>Substitute this into the first equation:</u>