Question

prove that sin780°.sin480°+cos240°.cos300°=1/2​

Answer 1

Step-by-step explanation:

And who art thou? Said I to the Soft-falling shower, Which, strange to tell, gave me an Answer, as here translated: I am the Poem of the Earth, said the Voice of the rain What does the poem mean by Who art thou? Who is the poet of the above poem? What was strange in the reply of the rain to the poet? Who is the poem of the Earth?And who art thou? Said I to the Soft-falling shower, Which, strange to tell, gave me an Answer, as here translated: I am the Poem of the Earth, said the Voice of the rain What does the poem mean by Who art thou? Who is the poet of the above poem? What was strange in the reply of the rain to the poet? Who is the poem of the Earth?And who art thou? Said I to the Soft-falling shower, Which, strange to tell, gave me an Answer, as here translated: I am the Poem of the Earth, said the Voice of the rain What does the poem mean by Who art thou? Who is the poet of the above poem? What was strange in the reply of the rain to the poet? Who is the poem of the Earth?And who art thou? Said I to the Soft-falling shower, Which, strange to tell, gave me an Answer, as here translated: I am the Poem of the Earth, said the Voice of the rain What does the poem mean by Who art thou? Who is the poet of the above poem? What was strange in the reply of the rain to the poet? Who is the poem of the Earth?

Answer 2

Answer:

Sin780° = Sin(360 + 360 + 60)° = Sin60° = √3/2.

Sin480° = Sin(360 + 90 + 30)° = Cos30° = √3/2.

Cos240° = Cos(180 + 60)° = -Cos60° = -1/2.

Cos300° = Cos(270 + 30)° = Sin30° = 1/2.

So, Sin780° × Sin480° + Cos240° × Cos300°

= (√3)²/(2)² + (-1)(1)/(2)².

= (3/4) - (1/4).

= (3 - 1)/4.

= 2/4.

= 1/2.

Hence Proved.

Hope this helps!!