Mathematics
Grade 10
15 min
Reasonable temperature - Celsius and Fahrenheit
Reasonable temperature - Celsius and Fahrenheit
Tutorial Preview
1
Introduction & Learning Objectives
Learning Objectives
Model the linear relationship between Celsius and Fahrenheit on a coordinate plane.
Construct a right triangle using two points on the temperature conversion line to represent temperature change.
Apply the Pythagorean theorem to calculate the straight-line distance between two temperature data points on a graph.
Use the tangent function to determine the angle of inclination of the Fahrenheit-Celsius conversion line.
Convert temperatures between Celsius and Fahrenheit to determine if a given temperature is reasonable for a specific context (e.g., weather, body temperature).
Interpret the slope of the conversion line as the ratio of the legs of a right triangle.
Your friend from Europe says it's 25°C outside. Should you pack a jacket or shorts? ☀️ Let&...
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Key Concepts & Vocabulary
TermDefinitionExample
Celsius (°C)A metric unit for measuring temperature, where 0°C is the freezing point of water and 100°C is the boiling point.A comfortable room temperature is about 20°C.
Fahrenheit (°F)An imperial unit for measuring temperature, where 32°F is the freezing point of water and 212°F is the boiling point.A comfortable room temperature is about 68°F.
Linear ConversionA relationship between two variables that can be represented by a straight line on a graph. The formula for converting Celsius to Fahrenheit is a linear equation.The equation F = (9/5)C + 32 graphs as a straight line, not a curve.
Slope as a Ratio (Rise/Run)The slope of a line measures its steepness and is the ratio of the vertical change (rise) to the horizontal change (run). In our context, it's the c...
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Core Formulas
Celsius to Fahrenheit Conversion
F = \frac{9}{5}C + 32
Use this formula to convert a known temperature in degrees Celsius (C) to its equivalent in degrees Fahrenheit (F). The slope is 9/5.
Fahrenheit to Celsius Conversion
C = \frac{5}{9}(F - 32)
Use this formula to convert a known temperature in degrees Fahrenheit (F) to its equivalent in degrees Celsius (C).
Pythagorean Theorem for Temperature Points
d^2 = (\Delta C)^2 + (\Delta F)^2
To find the geometric distance (d) between two temperature points (C1, F1) and (C2, F2) on a graph. ΔC is the change in Celsius (C2 - C1) and ΔF is the change in Fahrenheit (F2 - F1). These are the legs of the right triangle.
Angle of Inclination from Slope
\tan(\theta) = m = \frac{\Delta F}{\Delta C}
The tangent of the angle of...
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Challenging
A right triangle is formed on the C-F graph such that its hypotenuse lies on the conversion line. The geometric distance (length of the hypotenuse) is exactly √106 units. What are the lengths of the triangle's legs, ΔC and ΔF?
A.ΔC = 5, ΔF = 9
B.ΔC = 1, ΔF = 10.25
C.ΔC = 9, ΔF = 5
D.ΔC = 10, ΔF = 6
Challenging
If the axes of the temperature graph were swapped, so that Celsius (C) is plotted on the y-axis and Fahrenheit (F) is on the x-axis, what would be the new angle of inclination for the conversion line? Round to two decimal places.
A.60.95°
B.-60.95°
C.119.05°
D.29.05°
Challenging
A student calculates the angle of inclination for the F vs. C line and gets an answer of approximately 1.06. What is the most likely reason for this incorrect answer?
A.They used the sine function instead of the tangent function.
B.Their calculator was in radian mode instead of degree mode.
C.They used the slope of the C vs. F line by mistake.
D.They forgot to add 32 before calculating the slope.
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