first, find the numeric value for 11/15
second to find theta, simply do the <em>inverse</em> cos (which is cos^-1) of the first answer.
now you know theta, just do the sin of 90 - theta and that's it!
since you know whatr cos(theta) is, you just take the inverse cos of that number to get theta and 'reverse' cos, essentially. you are just solving for theta, by reversing the cos function with cos^-1
please mark as brainliest!