Do three sets of trigonometry problems. Such as if angle a + angle b + angle c equals 180 degrees solve the following problems. If angle A is 60 and angle b is 30 what is angle c? This is a right angled triangle. The character in the movie about that English code breaking machine tried to explain something once to someone. He kept leaving letters at Buckhead Palace. I never did. Did you? It was something about the need for motorways and a ring road or North Circular Road and 24 hour tube service. He was 98 and left a letter at a police station about his machine that would build the road. He is not dead. He is in Skegness at a Fish Shop on the High Road. All angles in this right angled triangle add up to 180 degrees. I am not trying to tell anyone anything.