Law of cosine:
c² = a² +b² -2ab*cosC.
Because the triangle is equilateral a=b=c=x,
and we can write,
x²=x² +x² -2xx*cosC
x² =2x² -2x²* cos C
-x² = -2x²*cos C
cos C= 1/2,
so m∠C=60⁰.
Because all sides are equal, and across of the equal sides should be equal angles, all angles will be also equal and = 60⁰.
You have something resembling a Riemann sum. Multiply through the summand by 1/n², then you can write
Answer:
x < 6.5
y < -1.5
Step-by-step explanation:
y > x - 8
Therefore x < y + 8
y < 5 - x
Therefore x < 5 - y
2x < 13
x < 6.5
6.5 < 5 - y
y < -1.5
