Q. 134.3( 10 Votes )

# Prove that

Answer :

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Using the formula,

sinA + sinB = 2sin cos

cosA + cosB = 2coscos

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In a ΔABC, if prove that the triangle is isosceles.

RD Sharma - MathematicsIn a Δ ABC, if ∠B = 60^{o}, prove that (a + b + c) (a – b + c) = 3ca

For any Δ ABC show that –

= (a+b+c)^{2}

Two ships leave a port at the same time. One goes 24 km/hr in the direction N 38^{o} E and other travels 32 km/hr in the direction S 52^{o} E. Find the distance between the ships at the end of 3 hrs.

In a Δ ABC cos^{2}A + cos^{2} B + cos^{2} C = 1, prove that the triangle is right angled.

In any Δ ABC, then prove that

RD Sharma - MathematicsIn a Δ ABC cos^{2}A + cos^{2} B + cos^{2} C = 1, prove that the triangle is right angled.

Two ships leave a port at the same time. One goes 24 km/hr in the direction N 38^{o} E and other travels 32 km/hr in the direction S 52^{o} E. Find the distance between the ships at the end of 3 hrs.

In any Δ ABC, then prove that

RD Sharma - MathematicsFor any Δ ABC show that -

RD Sharma - Mathematics