# Tutor profile: Katy U.

## Questions

### Subject: SAT II Mathematics Level 2

What is an equation of a line perpendicular to the line 2y = 4x + 9 ?

The first thing to do is to rearrange the equation into a y= form. This results in y = 2x + 4.5 A perpendicular line has a slope that is the negative reciprocal of the slope of the line. This means that the slope of the line is -0.5 Thus, any line with the slope -0.5 will be perpendicular to the line in the question. For example y = -0.5x + 3

### Subject: Pre-Calculus

tan(π/4) = 1 tan(π/6) = √3 / 3 What is the tan (π/12) ?

Using the angle-difference identity for tangent, we can see that tan ((π/4)-(π/6)) = tan (π/12). This means that tan (π/12) = (tan(π/4) - tan(π/6)) / (1 + tan(π/4)*tan(π/6)) = (1 - √3 / 3) / (1 + 1*√3 / 3) =(3-√3) / (3 + √3) =0.2680

### Subject: Basic Chemistry

Describe the type of bonding exhibited by NaCl.

NaCl exhibits ionic bonding. This is an electrostatic attraction between two oppositely charged ions. In this case, Na+ is a positive ion, or cation, and Cl- is a negative ion, or anion.

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