If u can recall the formula for Pythagoras’ in a right angle triangle. Its a^2 + b^2 = c^2 , where C is the hypotenuse. As you can tell from the question , we have been given 2 sides. Now you will need to look at the question is asking for, its asking for the hypotenuse, so we have side a and b and need to find c. Now substitute the two length 4 and 3 into the letters a and b of the equation. 4^2 + 3^2 = c^2. So c^2 = 16 + 9. c^2 = 25. No you square root both side of the equation. So the square root of c^2 is C and square root of 25 is 5. So c = 5 , so the hypotenuse is 5cm