Question

Given this unit circle, what is the value of x? (x, -7/10)(1,0)​

Answer 1

Answer:

x = - $\frac{\sqrt{51} }{10}$

Step-by-step explanation:

the equation of a circle centred at the origin is

x² + y² = r² ( r is the radius )

The radius of a unit circle is r = 1

substitute (x, - $\frac{7}{10}$ ) into the equation and solve for x

x² + (- $\frac{7}{10}$ )² = 1²

x² + $\frac{49}{100}$ = 1 ( subtract $\frac{49}{100}$ from both sides )

x² = 1 - $\frac{49}{100}$ = $\frac{51}{100}$ ( take square root of both sides )

x = ± $\sqrt{\frac{51}{100} }$ = ± $\frac{\sqrt{51} }{10}$

since the point is in the 3rd quadrant then x < 0

x = - $\frac{\sqrt{51} }{10}$