Nilai dari.. sin 135° sec 210° + cos 135° cot 225° = ?
Matematika
AnjaniSP
Pertanyaan
Nilai dari..
sin 135° sec 210° + cos 135° cot 225° = ?
sin 135° sec 210° + cos 135° cot 225° = ?
1 Jawaban
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1. Jawaban asobri68
Diketahui :
Jika ;
sin 135° = cos (90° - 135°)
= cos (-45°)
= cos (45°)
= √2/2
sec 210° = 1/ cos (210°)
cos 210° = cos (180° + 30°)
= cos (180°) cos (30°) - sin (180°) sin (30°)
= (-1)*(√3/2)-(0)*(1/2)
= -√3/2
Maka :
sin 135° sec 210° = sin (135°)*(1/ cos (210°))
= cos (-45°)*(1/ cos (210°))
= cos (45°) / cos (210°)
= (√2/2)/(-√3/2)
= -√2/3
Jika ;
cos (135°) = sin (90° - 135°)
= sin (-45°)
= -sin (45°)
= -√2/2
cot (225°) = 1 / tan (225°)
= 1 / tan (225° - 180°)
= 1 / tan (45°)
= 1/ 1
Maka ;
cos (135°)*cot (225°) = sin (-45°)*(1/ tan (225°))
= -sin (45°)/ tan (45°)
= - ((√2/2)/1)
= -√2/2
Ditanya :
sin (135°) sec (210°) + cos (135°)*cot (225°) = ???
Dijawab :
= sin (135°) sec (210°) + cos (135°)*cot (225°)
= cos (45°) / cos (210°) + -sin (45°)/ tan (45°)
= ((√2/2)/(-√3/2)) + (- ((√2/2)/1))
= -√2/3 - √2/2