You can use the sum and difference identities which for cosine is cos(a+b)= cosacosb-sinasinb
Answer: 64% of the variability in weight can be explained by the relationship with height.
Step-by-step explanation:
- In statistics, Correlation coefficient is denoted by 'r' is a measure of the strength of the relationship between two variables.
- Coefficient of determination,
, is a measure of variability in one variable can be explained variation in the other.
Here, r= 0.80

That means 64% of the variability in weight can be explained by the relationship with height.
The answer for your question is B. 5