Trig Fns - Identities
Interactive practice questions
Given that $\sin A=\frac{24}{25}$sinA=2425 and $\cos B=\frac{20}{29}$cosB=2029, find the exact value of:
a
$\sin\left(A+B\right)$sin(A+B)
b
$\cos\left(A-B\right)$cos(A−B)
Easy
10min
Find the value of $\sin20^\circ\cos40^\circ+\sin40^\circ\cos20^\circ$sin20°cos40°+sin40°cos20° in exact form.
Easy
1min
Using the expansion of $\cos\left(A+B\right)$cos(A+B), find the exact value of $\cos75^\circ$cos75°. Express the value in rationalised form.
Easy
3min
Given that $\sin A=\frac{24}{25}$sinA=2425 and $\tan B=\frac{20}{21}$tanB=2021, where $A$A and $B$B are acute angles, find the exact value of:
Easy
11min
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