CBSE Class 10 Answered

IT'S AN ISOCELES RIGHT ANGLED TRIANGLE,

If this is a multiple correct answer question, then correct options are (b) and (c), but if it's single correct answer type questions,

BE CAREFUL TO FOLLOW AUTHENTIC BOOKS.

The expression, cosA = sinB/(2sinC), (assuming this is what you meant and not cosA = sin(B/2)/sinC)is equivalently converted by using laws of sine and cosine,

(b²+c² - a²)/(2bc) = b/(2c)

(b²+c² - a²) = b²

c² - a² = 0

a = c

So sinA = sinC

It's an isoceles triangle. Also,

cosA = sinB/(2sinC) = sinB/(2sinA)

2sinAcosA = sinB

sin2A = sinB              

2A = B

and A + B + C = 180

A + 2A + A = 180         .....since side a = c, hence, C A

A = 180/4 = 45

C = 45

B = 90

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