Triangle ABC is a right- angled triangle.
ADB is a straight line.
DA = DC
Angle BCD = 20°
Work out the size of the angle
marked x.
You must give reasons for each
stage of your working out

First step is to get rid of the square root. remember that a square root is the same as raising to the (1/2) power. see below: multiply exponents per exponent rules to get: remember you subtract exponents from the denominator and add exponents in the numerator so: simplify further: so a is the correct choice. if you don't understand this google exponent rules and it will you understand. look at the image results.