Find the length of AB from the right-angle triangle ABC. Angle ACB = 40 degrees and side BC = 15cm.

Label each of the sides using the angle BCA. Therefore, AC = Adjacent, BC = Hypotenuse and AB = Opposite. Use the anagram SohCahToa to identify the side that we have (BC) and the side we are looking for (AB). After ticking the letters of SohCahToa, we will now use the Sin fraction. Let Sin(40) = Opposite / Hypotenuse. Replace Opposite and Hypotenuse with x and 15. Sin(40) = x/15. To solve this equation, multiply both sides by 15. 15 Sin(40) = x. Calculate this figure using your calculator to find the Opposite side AB. The answer is 9.64 cm (2 decimal places).

AL

Related Maths GCSE answers

All answers ▸

How do I find the nth term of a sequence?


The Tour de France is 2162miles long. A cyclist knows his average speed his 12.37 miles/hour from his previous races. For the Tour de France the cyclist knows he will cycle for 10 hours a day. Estimate how many days it will take him to complete the race.


Each day Chen buys pasta or a sandwich. Where Pasta costs £3.20 and Sandwich costs £2.75. For 45 days, the relative frequency of Chen buying a sandwich was one fifth. Altogether, how much did he pay?


Factorise 2x^3=10x+12x^2