Can anybody me find the answers to this page? or any problems you know?

Given the following sampling distribution of one mean with a sample size 49, from a normally distributed population, find the population standard deviation, o.79828588912497

Can someone check if i did this correct. it’s number 4 if you’re wondering.

1. ∠1 is complementary to ∠2 and ∠3 is complementary to ∠2. subtraction property of equality 2. m∠1 + m∠2 = 90 and m∠3 + m∠2 = 90 substitution 3. m∠1 + m∠2 = m∠3 + m∠2 definition of complementary 4. m∠1 = m∠3 given