Advertisements
Advertisements
प्रश्न
Find the value of the following:
`(cos 70^circ)/(sin 20^circ) + (cos 59^circ)/(sin31^circ) + cos theta/(sin(90^circ - theta))- 8cos^2 60^circ`
उत्तर
cos 60° = `1/sqrt(2)`
`(cos 70^circ)/(sin 20^circ) = (cos(90^circ - 20^circ))/(sin 20^circ) = (sin 20^circ)/(sin 20^circ)` = 1
`(cos 59^circ)/(sin 31^circ) = (cos(90^circ - 31^circ))/(sin 31^circ) = (sin 31^circ)/(sin 31^circ)` = 1
`(cos theta)/(sin(90^circ - theta)) = cos theta/cos theta` = 1
`(cos 70^circ)/(sin 20^circ) + (cos 59^circ)/(sin31^circ) + cos theta/(sin(90^circ - theta))- 8cos^2 60^circ`
= `1 + 1 + 1 - 8(1/2)^2`
= `3 - 8 xx 1/4`
= 3 – 2
= 1
APPEARS IN
संबंधित प्रश्न
Without using trigonometric tables, evaluate the following:
`( i)\frac{\cos37^\text{o}}{\sin53^\text{o}}\text{ }(ii)\frac{\sin41^\text{o}}{\cos 49^\text{o}}(iii)\frac{\sin30^\text{o}17'}{\cos59^\text{o}\43'}`
Evaluate:
tan(55° - A) - cot(35° + A)
Find the value of x, if sin x = sin 60° cos 30° – cos 60° sin 30°
Evaluate:
`(sin35^circ cos55^circ + cos35^circ sin55^circ)/(cosec^2 10^circ - tan^2 80^circ)`
Use tables to find cosine of 26° 32’
Use tables to find the acute angle θ, if the value of tan θ is 0.4741
Evaluate:
`(5sin66^@)/(cos24^@) - (2cot85^@)/(tan5^@)`
Prove that:
`1/(1 + cos(90^@ - A)) + 1/(1 - cos(90^@ - A)) = 2cosec^2(90^@ - A)`
If \[\sec\theta = \frac{13}{12}\], find the values of other trigonometric ratios.
If ∆ABC is right angled at C, then the value of cos (A + B) is ______.
