Answer:
tan 45°.sin 30° - cot45° = −(1÷2) = −0.5
Explanation:
45° Corresponds to (π÷4) which is a remarkable measure
We are all supposed to learn by heart the values of it’s ‘sin’ , ‘cos’ , ‘tan’ and ‘cot’ .
the same apply to 30° (corresponds to (π÷6))
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So without a calculator:
tan 45° = 1
cot 45° = 1
sin 30° = 1/2
therefore ,
tan 45°.sin 30° - cot45° = 1 × (1÷2) − 1 = (1÷2) − 1 = −(1÷2) = −0.5