Explanation

• The sum of the three interior angles of a triangle is 180°.
• This rule applies to all types of triangles.
• If two angles are known, the third angle = 180° − (sum of the other two angles).
• It is a basic rule of geometry.
• This property is known as the Angle Sum Property.

Last updated 17 july 2026 by NA

Explanation

Given:

Increment in number = 20% of the number

Decrement in number = 20% of the new number

Concept used:

Net increase or decrease percent = {(Original number or Final number) - (Final number or original number) ÷ Original number} × 100

Calculation:

Let the original number be 100

When the number is increased by 20%

New Number = 100 + 20% of 100

⇒ 100 + 20

⇒ 120

Now, the number is decreased by 20%

Final number = New number – 20% of new number

⇒ 120 – 20% of 120

⇒ 120 – 24

⇒ 96

∴ Net Decrease in percentage = { (100 – 96) / 100} × 100

⇒ {4/100} × 100

⇒ 4%

∴ The net decrease percentage is 4%.

Last verified on 11-07-2026

Explanation

For any angle θ:  

sin²θ + cos²θ = 1

Last verified on 09-05-2026

Explanation

Given sinθ = 3/5, 1st quadrant

Use identity: sin²θ + cos²θ = 1

(3/5)² + cos²θ = 1  

9/25 + cos²θ = 1  

cos²θ = 1 - 9/25 = 16/25  

cosθ = ±4/5

In 1st quadrant both sin and cos are positive.  

So cosθ = 4/5.

Last verified on 04-05-2026

Explanation

Area of a triangle = 1/2 _ base _ height

Let old base = B, old height = H.  

Old area = 1/2 _ B _ H

New base = B + 25% of B = B + 0.25B = 1.25B  

New height = H - 20% of H = H - 0.20H = 0.80H

New area = 1/2 _ 1.25B _ 0.80H  

= 1/2 _ 1.00 _ B _ H  

= 1/2 _ B * H

New area = old area. It stays the same.

Last verified on 25-05-2026

Explanation

Put a = 1 into a² + b² = 170.

1² + b² = 170  

1 + b² = 170  

b² = 170 - 1  

b² = 169  

b = 13 or b = -13

So b equals 13 or -13.

Last verified on 25-05-2026

Explanation

A triangle is classified based on its angles.

If one angle is 90°, it is a right-angled triangle.

The given triangle has angles 30°, 60°, and 90°.

Since it contains a 90° angle, it is a right triangle.

Last verified on 25-05-2026

Explanation

Write (14x + 10)/(x(x + 5)) = A/x + B/(x + 5)

Multiply both sides by x(x + 5):

14x + 10 = A(x + 5) + Bx

Now find A and B by plugging in values for x:

Put x = 0:

14_0 + 10 = A(0 + 5) + B_0

10 = 5A

A = 2

Put x = -5:

14_(-5) + 10 = A(0) + B_(-5)

-70 + 10 = -5B

-60 = -5B

B = 12

So (14x + 10)/(x(x + 5)) = 2/x + 12/(x + 5)

Last verified on 25-05-2026

Explanation

For f(x) = x² - x, find f(5) and f(3) separately then subtract.

f(5) = 5² - 5 = 25 - 5 = 20  

f(3) = 3² - 3 = 9 - 3 = 6  

Now f(5) - f(3) = 20 - 6 = 14  

Last verified on 25-05-2026

Explanation

y ∝ 1/x³ means y = k / x³ where k is a constant.

Step 1: Find k using y = 32 when x = 2

32 = k / 2³

32 = k / 8

k = 32 * 8 = 256

Step 2: Use k to find y when x = 4

y = 256 / 4³

y = 256 / 64

y = 4

Last verified on 25-05-2026