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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 WJEC GCSE Maths Exact trig values: explanations and worked examples.
1 of 5
What is the exact value of cos(90∘)+tan(45∘)\cos(90^\circ)+\tan(45^\circ)cos(90∘)+tan(45∘)?