In δabc, find the measure of ∡a rounded to the nearest tenth. triangle abc where angle c is a right angle. ab measures 26 point 3. ac measures 8 point 4. measure of angle a is unknown. 15.2° 18.6° 65.2° 71.4°

If you're looking for angle A, you need to set up your right triangle and see what trig identity you can use to find the missing A.  AB is the hypotenuse while AC is the base measure, and A is inbetween them.  AC is adjacent to A while AB is the hyotenuse, so your identity is .  Do that on your calculator, using the inverse cos.  Hit 2nd then cos and you'll see this on your screen: and then enter your fraction and hit enter again to get that angle A is 71.4