Final answer:
To convert 5.9°C to Fahrenheit, use the formula F = (C × 9/5) + 32, which results in 42.62°F.
Step-by-step explanation:
To convert the temperature from degrees Celsius to degrees Fahrenheit, you can use the formula F = (C × 9/5) + 32, where F represents the temperature in Fahrenheit and C represents the temperature in Celsius. In this case, if Diane's temperature app shows a high of 5.9°C, the temperature in Fahrenheit can be calculated as F = (5.9 × 9/5) + 32. This comes to F = (10.62) + 32 which equals to 42.62°F.