If abc measures 90o , what is the measure of ac

The measure of AC is 180°

Step-by-step explanation:

Given:

ABC is a right angle triangle at ∠B=  90°

We can say ΔABC inscribed in semi-circle whose diameter is AC.

We need to measure the angle AOC

The angle is subtended by an arc at the center of a circle is double the angle subtended at any point on the circumference at same arc.

Therefore, ∠AOC=2 ∠ABC

∠AOC = 2 x 90

∠AOC = 180°

Hence, The measure of AC is 180°

assuming you mean addition: addition and subtraction are reverse operations.

step-by-step explanation:

introduction, methodology, results, discussion

step-by-step explanation:

an observational study is one which consists of actual observation to record data and then analyse the data.

there are a number of factors that should be analyzed before starting an observational study.

the main four factors are:

i) introduction:   this should be analysed to check whether the purpose of the study is correctly established and the data recorded are appropriate for the study

methodology:   the method of collecting the data, such as whether randomly selected, and whether sample size matches with the population to be studied, whether questions asked are easy to answer by common men, etc.

results: then results such as summary of data with comments should be studied thoroughly

discussion:   the last is the discussion, this can be either by management people or persons who are all interested , etc.