Question

Without using trigonometric tables,find the value of cos 70/sin 20+cos 57.cosec 33-2 cos 60

Answer 1

Answer:

Step-by-step explanation:

Answer 2

Answer:

$Value \:of \\\frac{cos70}{sin20}+cos57\cdot cosec33-2cos60=1$

Step-by-step explanation:

$Value \:of \\\frac{cos70}{sin20}+cos57\cdot cosec33-2cos60$

$=\frac{cos(90-70)}{sin20}+cos57\cdot cosec(90-57)-2cos60$

$=\frac{sin20}{sin20}+cos57\cdot sec57-2\times \frac{1}{2}$

/* we know that,

i) cosA × secA = 1

ii) cos60° = 1/2 */

$=1+1-1\\=1$

$Value \:of \\\frac{cos70}{sin20}+cos57\cdot cosec33-2cos60=1$

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