Question 1206589: I am having trouble figuring this out and would appreciate some help.
Use Heron's formula to find the area of the triangle.
A = 79°, b = 73, c = 41
Thank you!
Found 3 solutions by ikleyn, MathLover1, math_tutor2020: Answer by ikleyn(52817) (Show Source):
You can put this solution on YOUR website! .
I am having trouble figuring this out and would appreciate some help.
Use Heron's formula to find the area of the triangle.
A = 79°, b = 73, c = 41
Thank you!
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In this problem, two sides of a triangle are given, "b" and "c", and the concluded angle A
between them.
For such case, there is very simple formula for the triangle area
area = .
By applying it, you get
area = = 1469.00508 square units (rounded).
So, doing this way, you get the answer directly, making minimum calculations,
which is considered as a right/rational way in Math.
Regarding this instruction on using the Heron's formula,
it is possible, but it requires much more calculation job:
- you first need to find the side "a", opposite to angle A, using
the cosine law;
- then you need to apply the Heron's formula, which is complicated itself.
So, this way requires much more calculations, making unnecessary job.
Therefore, I would call this way irrational.
Anybody in the theme, will say you that this way is possible, BUT using it is more than strange.
However, for those who like to do unnecessary work, this may seem attractive.
Answer by MathLover1(20850) (Show Source): Answer by math_tutor2020(3817) (Show Source):
You can put this solution on YOUR website!
Answer: 1469.00508 (approximate)
Round this however your teacher instructs.
Explanation
There is a shortcut as ikleyn points out, but it's clear from the instructions that the teacher requires Heron's formula.
I would follow the teacher's instructions to avoid losing points.
Heron's formula is only possible if we know all 3 sides of the triangle.
We're missing side 'a', but can find it using the Law of Cosines.
a^2 = b^2 + c^2 - 2*b*c*cos(A)
a^2 = 73^2 + 41^2 - 2*73*41*cos(79)
a^2 = 5867.817353676
a = sqrt(5867.817353676)
a = 76.60167983586
a = 76.60168
The result is approximate.
Please make sure that your calculator is set to degrees mode.
Now that we know all 3 sides, we can finally use Heron's formula.
The formula is:
A = sqrt(s*(s-a)*(s-b)*(s-c))
where,
s = semi perimeter = half the perimeter
s = (a+b+c)/2
s = (76.60168+73+41)/2
s = 95.30084
This value is approximate since 'a' was approximate.
Then,
A = sqrt(s*(s-a)*(s-b)*(s-c))
A = sqrt(95.30084*(95.30084-76.60168)*(95.30084-73)*(95.30084-41))
A = 1469.00508
This result is approximate.
The precision will depend on the precision of variable 'a'.
Round the answer however your teacher instructs.
I used GeoGebra to verify the answer.
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