Home
Class 10
MATHS
Without using trigonometric table, the v...

Without using trigonometric table, the value of
`cotthetatan(90^(@)-theta)-sec(90^(@)-theta)"cosec"theta+sin^(2)65^(@)+sin^(2)25^(@)+sqrt3tan5^(@)tan85^(@)`.

Text Solution

AI Generated Solution

The correct Answer is:
To solve the expression \[ \text{cottheta} \cdot \tan(90^\circ - \theta) - \sec(90^\circ - \theta) \cdot \csc \theta + \sin^2 65^\circ + \sin^2 25^\circ + \sqrt{3} \tan 5^\circ \tan 85^\circ, \] we will break it down step by step. ### Step 1: Simplify the first part The first part of the expression is \[ \text{cottheta} \cdot \tan(90^\circ - \theta). \] Using the trigonometric identity, we know that \[ \tan(90^\circ - \theta) = \cot \theta. \] Thus, \[ \text{cottheta} \cdot \tan(90^\circ - \theta) = \cot \theta \cdot \cot \theta = \cot^2 \theta. \] ### Step 2: Simplify the second part Next, we simplify \[ -\sec(90^\circ - \theta) \cdot \csc \theta. \] Using the identity, we have \[ \sec(90^\circ - \theta) = \csc \theta. \] Thus, \[ -\sec(90^\circ - \theta) \cdot \csc \theta = -\csc \theta \cdot \csc \theta = -\csc^2 \theta. \] ### Step 3: Combine the first two parts Now we can combine the results from Step 1 and Step 2: \[ \cot^2 \theta - \csc^2 \theta. \] Using the identity \[ \csc^2 \theta - \cot^2 \theta = 1, \] we can rearrange this to: \[ \cot^2 \theta - \csc^2 \theta = -1. \] ### Step 4: Simplify the sine squares Next, we simplify \[ \sin^2 65^\circ + \sin^2 25^\circ. \] Using the identity \(\sin^2 A + \sin^2 B = 1 - \frac{1}{2}(\cos(2A) + \cos(2B))\), we can compute: \[ \sin^2 65^\circ + \sin^2 25^\circ = \sin^2 65^\circ + \cos^2 65^\circ = 1. \] ### Step 5: Simplify the tangent product Now we simplify \[ \sqrt{3} \tan 5^\circ \tan 85^\circ. \] Using the identity \(\tan(90^\circ - \theta) = \cot \theta\), we have \[ \tan 85^\circ = \cot 5^\circ. \] Thus, \[ \tan 5^\circ \tan 85^\circ = \tan 5^\circ \cdot \cot 5^\circ = 1. \] Therefore, \[ \sqrt{3} \tan 5^\circ \tan 85^\circ = \sqrt{3} \cdot 1 = \sqrt{3}. \] ### Step 6: Combine all parts Now we can combine all parts of the expression: \[ -1 + 1 + \sqrt{3} = \sqrt{3}. \] Thus, the final answer is \[ \sqrt{3}. \]
Doubtnut Promotions Banner Mobile Dark
|

Topper's Solved these Questions

  • INTRODUCTION TO TRIGONOMETRY

    CBSE COMPLEMENTARY MATERIAL|Exercise LONG ANSWER TYPE QUESTIONS|10 Videos
  • INTRODUCTION TO TRIGONOMETRY

    CBSE COMPLEMENTARY MATERIAL|Exercise PRACTICS-TEST (SECTION-A)|4 Videos
  • INTRODUCTION TO TRIGONOMETRY

    CBSE COMPLEMENTARY MATERIAL|Exercise SHORT ANSWER TYPE (I) QUESTIONS|15 Videos
  • CONSTRUCTIONS

    CBSE COMPLEMENTARY MATERIAL|Exercise (PRACTICE-TEST) SECTION-C|1 Videos
  • PAIR OF LINEAR EQUATIONS IN TWO VARIABLES

    CBSE COMPLEMENTARY MATERIAL|Exercise PRACTICE-TEST (SECTION-D)|1 Videos

Similar Questions

Explore conceptually related problems

cot theta tan(90^@-theta)-sec(90^@-theta)cosec theta+sqrt3 tan12^@ tan 60^@ tan78^@=2

Write the value of "cosec"^(2)(90^(@)-theta)-tan^(2)theta.

Knowledge Check

  • The value of cottheta.tan(90^(@)-theta)-sec(90^(@)-theta)cosectheta+(sin^(2)25^(@)+sin^(2)65^(@)) is

    A
    1
    B
    `-1`
    C
    2
    D
    0
  • The value of cot theta.tan (90^@ -theta)-sec(90^@ - theta) cosec theta+ (sin^2 25^@+sin^2 65^@) +sqrt3(tan 5^@ tan15^@.tan30^@.tan75^@.tan85^@) is

    A
    1
    B
    `-1`
    C
    2
    D
    0
  • tan^(2)(90^(@) - theta) - cosec^(2) theta =

    A
    0
    B
    1
    C
    -1
    D
    2
  • Similar Questions

    Explore conceptually related problems

    Without using trigonometric tables , evaluate the following : (cot(90^(@)-theta)*sin(90^(@)-theta))/(sintheta)+(cot40^(@))/(tan50^(@))-(cos^(2)20+cos^(2)70^(@))

    Without using trigonometric tables, evaluate each of the following: (-tanthetacot(90^0-theta)+secthetacos e c(90^0-theta)+sin^2 35^0+sin^2 55^0)/(tan10^0tan20^0tan30^0tan70^0tan80^0)

    Without using trigonometrical tables; prove (sin theta)/(sin(90-theta))+(cos theta)/(cos(90^(@)-theta))=sec theta*cosec theta

    Without using trigonometric tables,find the value of the following expression: (sec(90-theta)*cos ec theta tan(90-theta)cot theta+cos^(2)25+cos^(2)65)/(3tan27^(@)*tan63^(@))

    What is the value of cosec (65^(@) + theta) - sec(25^(@) - theta) + tan^(2) 20^(@) - cosec^(2) 70^(@) ?