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In a right-angled triangle, the hypotenuse is opposite the right angle. Relative to the chosen angle θ\thetaθ, the other sides are called opposite and adjacent.
SOHCAHTOA tells you that sinθ=oppositehypotenuse\sin\theta=\frac{\text{opposite}}{\text{hypotenuse}}sinθ=hypotenuseopposite, cosθ=adjacenthypotenuse\cos\theta=\frac{\text{adjacent}}{\text{hypotenuse}}cosθ=hypotenuseadjacent and tanθ=oppositeadjacent\tan\theta=\frac{\text{opposite}}{\text{adjacent}}tanθ=adjacentopposite. In triangle questions, label the sides first and then choose the ratio.
An exact value is written with no rounding. So sin(45∘)=22\sin(45^\circ)=\frac{\sqrt{2}}{2}sin(45∘)=22 is exact, while 0.7070.7070.707 is only an approximation.
Question 1
1 markWrite down the exact value of sin(45)\sin(45)sin(45)
What defines an exact value in trigonometry?
Revision notes for Edexcel GCSE Maths Exact trig values. Open the guide for explanations and worked examples. Written against the Edexcel GCSE Maths (1MA1) specification, so the content matches what's examinable rather than general Maths background.
1 of 5
What is the exact value of cos(90∘)+tan(45∘)\cos(90^\circ)+\tan(45^\circ)cos(90∘)+tan(45∘)?
