Friday

October 31, 2014

October 31, 2014

Posted by **qwerty123** on Monday, March 21, 2011 at 6:30pm.

- Geometry -
**Reiny**, Monday, March 21, 2011 at 8:06pmextend AM its own length of 3.5 to point D.

Join BD and CD

You now have a quadrilateral where the diagonals AD and BC bisect each other.

So ABDC must be a parallelogram .

In triangle ADC you could now use the cosine law to find angle DAC

Once you have that you can use the cosine law again to find MC in triangle AMC

double MC to find BC

- Geometry -
**tchrwill**, Tuesday, March 22, 2011 at 9:36amTriangle ABC, A at the top, B & C at the bottom, B left & C right.

The length of a triangle median is defined by

(Ma)^2 = (b^2 + c^2)/2 - a^2/4. (Ma is the median from vertex A to side "a".)

(Mb)^2 = (a^2 + c^2)/2 - b^2/4

(Mc)^2 = (a^2 + b^2)/2 - c^2/4

Letting BC = a, AB = c = 4, AC = b = 7 and AH = 3.5

Then, (3.5^2) = (7^2 + 4^2)/2 - a^2/4

Multiplying through by 4 yields 4(3.5)^2 = 2(49 + 16) - a^2 or

49 = 130 - a^2 or a^2 = 130 - 49 = 81 making a = 9 = BC.

**Answer this Question**

**Related Questions**

geometry - The sum of the lengths of the sides of triangle ABC is 25 in. The ...

geometry - Triangle ABC and triangle XYZ are similar. If AB, BC, and AC are 7 ...

Math - The sum of the lengths of the sides of triangle ABC is 38in. The length ...

math - The hypotenuse of a triangle is 13 inches long. Which of the follwoing ...

Math - 1) what is the length of the diagonal of a square whose sides are 3 ...

Geometry - The lengths of the sides of a triangle are 3,5, and 7 inches. How ...

Algebra 2 - Can you double check my answer The lengths of the sides of a ...

Math - The hypotenuse (side C) of a triangle is 13 inches long. Which of the ...

geometry - Two sides of a triangle measure 4 inches and 9 inches. Determine ...

geometry - what is the perimeter of a triangle whose sides measure 7 3/4 inches,...