The question is misleading. I assume angle A is 50 degrees and angle B is 30 degrees (and therefore the third angle, which I'll call C, is 180 - 50 - 30 = 100 degrees), and the length of side "a" is 1.
Why would you ask this question? Lol for one, no triangle has a total internal angle measure of 81°, and further, giving the angles alone is not good enough to find the area of a triangle as there are an infinite amount of similar triangles with those measures.
Answers & Comments
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Triangle ABC has interior angles (A,B,C) = (50,30,100)°. Sides opposite
(A,B,C) are (a,b,c,). a = 1. Law of sines says a/sinA = b/sinB = c/sinC, ie.,
1/sin50 = b/sin30 = c/sin100. Then b = sin30/sin50 and c = sin(100)/sin50,
ie., b = 1/(2sin50) and c = 2sin50cos50/sin50 = 2cos50. Then (a,b,c) =
(1, 0.6527036447, 1.285575219). s = (1/2)(a+b+c) = 1.469139432,
(s-a) = 0.4691394320, (s-b) = 0.8164357874, (s-c) = 0.1835642127.
Now, by Heron's formula, A^2 = s(s-a)(s-b)(s-c), where A is the area of triangle ABC. A^2 = (1.469139432)(0.4691394320)(0.8164357874)*
(0.1835642127) = 0.1032939778 and A = 0.313938048 square units.
The area of a triangle (to the nearest hundredth) with internal angles of
A = 50, B = 30, a = 1:
Area = 0.32139
apply law of Sin to solve for side b
.... a............b
--------- = ---------
.sinA........sinB....
...1.............b
--------- = ---------
.sin(50)...sin(30)
sin(30) = bsin(50)
b = 0.65
solving for Angle C
m∠C + 50 + 30 = 180
m∠C +80 = 180
m∠C = 180 - 80
m ∠C = 100°
Now solving the Area of triangle using this formula
Area = 1/2absinC
Area = 1/2(1)(0.65)sin(100)
Area = 0.32 square unit.. Answer//
Online triangle calculator:
Sides: a = 1 b = 0.653 c = 1.286
Area: T = 0.321
Perimeter: p = 2.938
Semiperimeter: s = 1.469
Angle ∠ A = α = 50° = 0.873 rad
Angle ∠ B = β = 30° = 0.524 rad
Angle ∠ C = γ = 100° = 1.745 rad
Answer:
0.32 sq. units (to the nearest hundredth)
The question is misleading. I assume angle A is 50 degrees and angle B is 30 degrees (and therefore the third angle, which I'll call C, is 180 - 50 - 30 = 100 degrees), and the length of side "a" is 1.
In that case, the area is:
T = a^2 / (2(cot(B) + cot(C)))
T = 1^2 / (2(cot(30) + cot(100)))
T =~ 0.3214
Why would you ask this question? Lol for one, no triangle has a total internal angle measure of 81°, and further, giving the angles alone is not good enough to find the area of a triangle as there are an infinite amount of similar triangles with those measures.
depends on how the surface is curved..
assuming those numbers refer to degrees
Simple calculator here
https://www.triangle-calculator.com/
(1/2) ( w / 2 ) where w = sin 100° / sin 50° ( base)