Consider the right angled triangle with vertices labelled a, b, c. Angle A = 60°, Angle B = 90°, length ab=4cm, length ac=xcm. If cos60° = 0.5, work out the value of x.

The first thing to do in such a question is to draw out the information you have been given. Not only does this help to process the question again, so that no vital information is missed, but also makes it a lot easier to see how to go about solving the problem.The trigonometric rule of 'SOH-CAH-TOA' can then be applied. My useful hint to remember this is 'Silly Old Hitler, Caused Awful Havoc, Too Our Armies'In this question we are given information on the Cosine, Adjacent and Hypotenuse. Therefore 'CAH' is the part we need. (Cos60° = adjacent/hypotenuse) When we sub in the values given, we see 0.5=4/x, which can be rearranged to x= 4/0.5, so x=8cm.

RR
Answered by Rebecca R. Maths tutor

4540 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Aled has three concrete slabs. Two of the slabs are square, with each side of length x metres. The third slab is rectangular and measures 1 metre by (x +1) metres. The three concrete slabs cover an area of 7m^2. Show that 2x^2 + x – 6 = 0. Find x.


Solve the simultaneous equations. 2x + y =10 and x + y = 4


How do I work out probability when a random choice is repeated?


Solve equations 2x+y=9 and x+2y=6 to find x and y.


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences