Question

The value of $cos^{2}17^{0}-sin^{2}73^{0}$ is
(a)1
(b)$\frac{1}{3}$
(c)0
(d)−1

Answer 1

SOLUTION :  

The correct option is  (c)  : 0 .

Given : cos² 17° - sin² 73°  

cos² 17° - sin² 73°  

= cos² (90° - 73°) - sin² 73°  

= sin² 73° - sin² 73°  

[ cos (90° -θ ) = sin θ )]

= 0

cos² 17° - sin² 73° = 0  

Hence, the value of cos² 17° - sin² 73° is 0 .

★★Trigonometry is the study of the relationship between the sides and angles of a triangle.

★★ Two angles are said to be complementary if their sum is equal to 90° .

θ & (90° - θ) are complementary angles.

HOPE THIS ANSWER WILL HELP YOU…

Answer 2

Answer:

0

Step-by-step explanation:

Given Equation is cos²(17°) - sin²(73°)

= cos²(90 - 73) - sin²(73)

∴ We know that cos(90 - θ) = sinθ

= sin²(73) - sin²(73)

= 0.

Hope it helps!