Question

If sin theta +sin^2 theta +sin^3 theta = 1, prove that cos^6 theta -4 cos^4 theta +8 cos^2 theta =4

Answer 1

Answer:

Area of rectangle is 192 cm².

Step-by-step explanation:

Given :-

Length of rectangle is 16 cm.

Diagonal of rectangle is 20 cm.

To find :-

Area of rectangle.

Solution :-

First we will find breadth of rectangle because we do not have breadth of rectangle for area.

Let, rectangle be ABCD.

BC be length of rectangle.

AC be diagonal of rectangle.

And, AB be breadth of rectangle.

We know,

All angles of rectangle are of 90°.

So,

∆ABC is a right angle right. ∆ABC will right angled from B.

By Pythagoras theorem :

• Perpendicular² = Hypotenuse² - Base²

Perpendicular = AB

Hypotenuse = AC = 20 cm.

Base = BC = 16 cm.

Put all values in Pythagoras theorem :

⟶ (AB)² = (AC)² + (BC)²

⟶ (AB)² = (20)² + (16)²

⟶ (AB)² = 400 - 256

⟶ (AB)² = 144

⟶ AB = √144

⟶ AB = 12

Thus,

AB is 12 cm.

AB is perpendicular of ∆ABC and AB is breadth of rectangle ABCD.

So, Breadth of rectangle is 12 cm.

We know,

Area of rectangle = Length × Breadth

⟶ Area = 16 × 12

⟶ Area = 192

Therefore,

Area of rectangle is 192 cm².