Equation symbol is the name of what you are asking for
There is a theorem that says that this angle (formed by thre points on the circumference) is half such arc called EF.
We can deduct it as well.
1) Call O the center of the circle. The central angle (EOF) = arc EF = 151°
2) Draw a chord from F to D and other chord from D to E.
You have constructed two triangles, FOD and DOE.
3) Triangle FOD has two sides equals (because both are the radius of the circcle). Then, this is an isosceles triangle and it has two angles of the same measure. Call this measure a.
4) Triangle DOE is also isosceles, for the same reason explained in the poiint 3. Call the measure of its equal angles b.
5) The sum of the angles of the two triangles is 180° + 180 ° = 360°.
This is a + a + b + b + (360 - central angle) = 360°
=> 2a + 2b = central angle
=> 2(a+b) = cantral angle
=> (a+b) = central angle / 2 = 151° / 2 =71.5°
(a+b) is the angle that you are looking for.
Then the answer is 71.5°
Answer:
200√3
Step-by-step explanation:
The triangle given here is a special right triangle, one with angles measuring 30-60-90 degrees. The rule for triangles like these are that the side opposite the 30° angle can be considered x, and the side opposite the 60° angle is x√3, while the hypotenuse, or side opposite the right angle, is 2x. All we need to know here are the two legs to find the area.
Since b is opposite the 30° angle, it is x, while side RS is opposite the 60° angle, meaning it is equal to x√3, meaning that the area of the triangle is 1/2*x*x√3. We can substitute in 20 for x, making our area 1/2*20*20√3. Multiplying we get 10*20√3, or 200√3.
