Which equation is an identity?
2 answers:
Answer:
The correct option is 2.
Step-by-step explanation:
The equations that are true for any value of the variable, no matter what value is plugged in for the variable, then they are called Identity equations.
The first equation is
Subtract 7m from both the sides.
This statement is false for any value of m. Therefore this is not an Identity equation.
The second equation is
Using distributive property,
This statement is true for any value of w. Therefore this is an Identity equation.
The third equation is
This statement is false for any value of v. Therefore this is not an Identity equation.
The fourth equation is
Add 3y on both the sides.
This statement is false for any value of y. Therefore this is not an Identity equation.
Hence the correct option is 2.
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Answer:
30°
Step-by-step explanation:
Call the other end of the chord point B and the center of the circle point O. Then triangle AOB is an equilateral triangle, since OA = OB = AB.
Angle OAB is the internal angle of that triangle, so is 60°. Since OA is perpendicular to the tangent line (makes an angle of 90°), The angle between the tangent line and the chord must be ...
90° - 60° = 30°
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The other way you know this is that central angle AOB is 60°, and the tangent-to-chord angle is half that, or 30°.
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One way to remember the angle relationship between a tangent line and a chord is this:
Consider a point C on long arc AB. The measure of inscribed angle ACB is half the measure of central angle AOB, no matter where C is on the circle. (If C happens to be on the short arc AB, then central angle AOB is a reflex angle, but the relationship still holds.) Consider what happens when C approaches A. The angle at vertex C is still the same: 1/2 the measure of central angle AOB. This remains true even in the limit when points A and C become coincident and line AC is a tangent at point A.
